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In Reply to: RE: Schitt buffer question posted by airtime on August 24, 2024 at 07:58:46
It's not a Schitt product, but the Topping Pre90 line-stage preamp has a relay controlled resistive volume attenuator that operates with 0.5-dB steps from -99-dB to +16-dB. This little preamp sounds as good as any preamp I've ever owned or heard.The Topping Pre90 is primarily designed as a balanced preamp, but it has unbalanced inputs and outputs, too. The main unit that incorporates the volume control has two sets of inputs and two sets of outputs. There's an extension unit that provides four additional sets of inputs. The main unit costs $527 from Amazon and the input extension unit costs $219.
With the extension unit connected, you will have a total of four pairs of balanced inputs and two pairs of unbalanced inputs. The outputs are buffered giving you a pair of balanced outputs and a pair of unbalanced outputs. I bought only the main unit because I didn't need the additional inputs.
Stereophile rated the Topping Pre90 as Class "A" in their most recent Recommended Components. It's my choice as the very best sounding preamp I've ever owned, replacing my Pass Labs X1 preamp. Based on your stated requirements, it sounds exactly like what you need.
Happy listening!
Edits: 08/24/24Follow Ups:
From the above Amazon review:
"I use the XLR out to my amp and initially had my sub connected to the RCA outs. This didn't work at all, the output broke onto a high frequency oscillation when the sub was turned on. The RCA cable is 12' long. Even with the sub off having the RCA cable connected affected the sound quality. I'm now feeding the sub high level from the power amp speaker outputs."
If I remember correctly, you run (or ran) a separate subwoofer amp, yes? If so, did you attempt to use both sets of outputs of the Topping Pre90 at once? I can't run my sub amp off my main amp (First Watt F1J)'s outputs. It's a rather unusual amp, so using both outputs on the Pre90 would be imperative for my needs. This would require the Pre90 to be able to drive a 5K load (main amp and sub amp in parallel).
Thanks.
I owned the Topping Pre90 and the EXT90 expansion box which is required if you want more than one set of inputs. As Kal Rubinson mentioned in his Stereophile review the Pre90 remote is frustrating. For me it wasn't just the need to point the remote precisely but the logic in the preamp itself didn't always respond to remote commands on the first try. I usually had to press a second time before the Topping Pre90 would 'wake up' and respond. Not just weird but very irritating.
I can imagine the poorly performing remote being frustrating, although I don't have a preamp remote now, so I'm already used to getting up to adjust my volume control.
Given that it has both balanced and unbalanced inputs, I would connect my phono stage to the balanced, and my DAC to the unbalanced. A third input would be welcomed for occasional FM tuner use, but I'm not willing to spend an extra $249 to get it.
My biggest concern at this point is the possible impedance issues. Once I'm convinced that the output impedances of my source components and the 5K load of my amps in parallel won't be an issue, I'll likely give the Pre90 a try.
Yes, the Topping Pre90 has two sets of outputs. They're buffered from each other, so you can drive a sub with one set and your main amps with the other set. That's what I'm doing right now. My Rythmik Servo Sub is connected to the unbalanced outputs and my Hypex Nilai 500 Mono Block Amplifiers are connected to the balanced outputs. My system sounds just fine.TW apparently had a defective Topping Pre90. Mine works just fine driving my monoblocks and my subwoofer simultaneously. Moreover, I have no problems with the remote control, either. As far as I'm concerned, the Topping Pre90 is absolutely the best line-stage control preamplifier that I have ever encountered. And, the price is unbelievable.
Good luck!
John ElisonEdit: I just ordered another Topping Pre90, this time with the extension unit. I really like this little preamp and it's unbelievably inexpensive relative to its exceptional performance.
Edits: 08/24/24
I wondered if the Amazon reviewer's Pre90 might be defective, which is why I asked.
Both my main amp and sub amp have a 10K input impedance, so if the Pre90 can drive a 5K load, that will be one consideration off my mind.
I've yet to read Kal's review in full, but the boys over at Audio Science Review pointed out the extremely low (according to them) input impedance of the Pre90, which apparently doesn't mate well with some components. I'll have to check the specs on both my phono stage and DAC. If they'll work with the Pre90 then I might order one.
Thanks again.
> Both my main amp and sub amp have a 10K input impedance, so if the Pre90 can drive a 5K load, that will be one consideration off my mind.
I could be wrong, but I believe the two outputs are individually buffered. Therefore, I don't think you would be connecting both amplifiers in parallel. In other words, each output would be driving a 10k-ohm load separately. However, I can't find anything in the specifications that answers this concern. Therefore, I think the only way you will know whether or not your system is compatible will be to try it, and most dealers allow you to return a product if you're not satisfied. I bought my Topping Pre90 from Amazon, which allows returns.
> I'll have to check the specs on both my phono stage and DAC. If they'll work with the Pre90 then I might order one.
The input impedance of the balanced inputs is rather low at 2k-ohms. However, my FiiO R9 sounds just fine connected to the Topping's balanced inputs.
The input impedance of the unbalanced inputs is 9.9k-ohms, which should work just fine with nearly all components.
Good luck!
John Elison
"I believe the two outputs are individually buffered"
Do you remember what caused you to draw that conclusion, John? Not that I've read everything out there on the Pre90, and I simply may have missed that description of how the circuit is configured.
Some of the responders to the Audio Science Review (a site I'd never been to prior to this) of the Topping Pre90 voiced similar concerns as mine regarding the low input impedance of the Pre90 measured in their review, questioning whether it would work with some "legacy" components. Or what we on the Asylum more often refer to as Vintage or Classic pieces of audio gear.
For 'sound quality', I'm certainly willing to trust my own ears, lest anyone draw a conclusion because I'm referencing Audio Science Review. But electrical laws do apply, and I'd like to be sure ahead of time that I'm not trying to fit a square peg in a round hole where the Pre90's 'unusual' impedance issues are concerned.
If buying and trying the Pre90 is the only way for me to have my questions answered, then I may have to go that route. But I'm trying to avoid having to send it back simply because I didn't do my homework in advance. Trying to find out information regarding potential electrical compatibility issues shouldn't be this difficult, in my estimation. For example, in the measurement section of Kal's review, John Atkinson wrote:
"The balanced input impedance was low, at 2k ohms from 20Hz to 20kHz, which might give a bass-light balance with source components that have a tubed output stage."
Rather than state something as ambiguous as "a tubed output stage", an actual range, like "I wouldn't use a source component with an output impedance below [insert number here] with the Pre90" would have been far more useful, in my estimation.
Thank you again, John. You and Kal Rubinson have both been very helpful in trying to address my concerns.
Sorry, I don't remember what caused me to think the two outputs were buffered. Perhaps they're not! However, the Pre90 drives my monoblocks and my subwoofer simultaneously without any audible problems that I can detect.
The outputs are individually activated. Perhaps this is why I thought they might also be individually buffered.
Since you seem to be so concerned about this feature, I would recommend looking for a different preamplifier. My Pass Labs X1 preamp has balanced and unbalanced outputs, and they are definitely individually buffered. At least that's explicitly stated in the owner's manual. This preamp originally cost $5,800, but I prefer the sound of the Topping Pre90. I feel the Topping Pre90 has a more transparent sound quality while the Pass Labs X1 sounds more like vacuum tubes. However, it definitely has individually buffered outputs and I'll be happy to sell it to you if you're interested.
Good luck!
I'm inclined to agree with you, John. Thanks.
Well, you could always do what Kal is doing. You could buy two Pre90's and connect one to your main speakers and the other to your subwoofer. Then you could use a Y-adapter to drive both preamps with the same input signal.
Kal bought three Pre90's to use as a volume control for his 5.1 channel home theater system.
As far as I'm concerned, my Pre90 is the best sounding preamp I've ever heard regardless of price, and it drives all my amplifiers just fine.
If you'd like to buy my Pass Labs X1 preamp, I'll be happy to sell it to you for $1,500 plus shipping. It definitely has buffered outputs and it also has a separate power supply. Of course, you could buy two Pre90's for $1200 and they'd probably sound better.
Good luck!
Your Pass X1 should go fast at that price.
"Well, you could always do what Kal is doing. You could buy two Pre90's and connect one to your main speakers and the other to your subwoofer. Then you could use a Y-adapter to drive both preamps with the same input signal."Or you could simply buy one and use the balanced and unbalanced outputs simultaneously fot the main pair and the sub. Been there, done that.
Sometimes, people completely overthink the issues, get distracted and, in desparation, make a poor choice. Been there, done that.
I think that you (Tod, not John) may be getting there.
Edits: 08/31/24
That's sometimes true, and I can be a notorious over-thinker about some things. But I don't believe my concerns over impedance qualify as unfounded concern, because it's not a subjective issue. I emailed Apos Inc. Someone named Peter got back to me, writing:
"Thanks for reaching out. Before giving you an answer, let me confirm with Topping on my thoughts. I don't want to tell you incorrect information, so I'll let you know as soon as I hear back from them.
I was impressed with how quickly they got back to me, and even more impressed that they didn't just say, "Don't worry about it. Just order one!" which is the advice I appear to be getting here.
I already have a buffered line stage called The Truth, which is reviewed at the link below. Regarding the Truth's impedances, here's what the manufacturer says about it:
"It has an input impedance too high to measure, output impedance is a couple ohms".
Too high to measure with a a common multi-meter anyway, and my meter measures up to 60 Megaohms. So a high input impedance, and a few ohms on the output, which assure me it's going to work with anything I connect to it. If I had that same confidence in the Pre90, I'd have ordered one by now.
The only reason I'm considering something other than my Truth is that I ordered it years ago, with only one set of inputs and outputs. A selector switch and two or three more pair of RCA jacks will remedy that, but I wasn't looking forward to doing the work. It looks like I'm going to have to rethink that, unless Apos has some good news for me.
> Or you could simply buy one and use the balanced and unbalanced outputs simultaneously for the main pair and the sub.
Kal: I agree with you wholeheartedly!
This is exactly what I do. My Hypex Nilai 500 monoblock amplifiers are connected to the Topping's balanced outputs and my Rythmik Servo Sub is connected to its unbalanced outputs. It works just fine for me.
Moreover, I don't even have a problem with its remote control.
Happy listening!
I've owned and used 3 of them. None failed or complained, even with subs.
Edits: 08/24/24
I've sent an email inquiry to Apos, addressing my concerns regarding the Pre90's input and output impedances. Hopefully they'll get back to me with some useful information.
The output impedance of the Pre90 is stated in the owner's manual to be 20-ohms for the unbalanced outputs and 40-ohms for the balanced outputs.
The input impedance is stated in Stereophile's Review Measurements to be 9.9k-ohms at 1000-Hz for the unbalanced inputs and 2k-ohms for the balanced inputs.
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