Amp/Preamp Asylum: REVIEW: Rogue Audio Stereo 90 Amplifier (Tube) by Rrecker Looking for a new Amp or Preamp? If you're after tubes, post over here.

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Model:	Stereo 90
Category:	Amplifier (Tube)
Suggested Retail Price:	$2,195 MSRP
Description:	90 watt Stereo Amplifier
Manufacturer URL:	Rogue Audio
Manufacturer URL:	Rogue Audio

Review by Rrecker ( A ) on February 04, 2007 at 04:24:50 IP Address: 71.154.208.94

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What? No Stereo 90 Reviews!?
To be honest I hated my Stereo 90 for the first 5 months I owned it. In fact, it came oh-so-close to ending up on "the Island of Unwanted Amplifiers" (aka Ebay/Audiogon). Ah, I still remember the first agonizing hours of listening. Violins were painful, anything with horns? Forget it. It was shrill, strident, bass anemic. I rolled tubes, bought new speakers, changed speaker cables and interconnects, I change CD Players 3 different times (Denon 2900, creek Evo and the MF A3.5) and while there were differences and sometimes very noticeable improvements; the Stereo 90 remained ...well...sonically horrid. To add injury to auditory insult, one day, the Stereo 90 developed a mechanical transformer hum. It was the Richard Gray RGPC 400 Pro that would save the Stereo 90 from the afore mentioned internet scrap heap. I still remember the salesman explaining how the Richard Gray worked as well as reading about it. At the time I thought it an absolutely preposterous theory. Besides I already had a very expensive Monster Cable line conditioner. Desperate, I tried the Richard Gray...talk about your night and day difference.... The sound I get now is very similar to a set of Grado RS 1 headphones tonally and detail wise; the sound stage is large, deep and anatomically correct. (Yes the RS 1s! with Grado wood block headphone amp!) The Stereo 90 makes it easy to bias the power tubes, I suspect my amp was under biased pre- Richard Gray. the bias needle used to oscillate so much I couldn’t really get an accurate setting. You can also change the output transformer impedance from 8 ohms to 4 ohms. My Adagios much prefer the 4 ohm tap, it was the treble and upper midrange that confirmed this change. As to tubes, I think I can make some useful comments. After the Rogues power supply requirements were satisfied, I re-rolled no less than 5 different types of power tubes. In my opinion none of the currently manufactured KT88s sound very good. (uh oh...flame war) The only set of power tubes I like are the NOS Jan Ge 6550s. (I haven’t tried the Tungsols). To my ears, these have the best bass, midrange , top end, with excellent transparency. The sound stage is greatly improved over the kt88s tubes They don’t sound “tubey’ and have excellent transient punch/slam. I would attribute part of the excellent sound quality coming from my “new and improved Stereo 90” to my choice of 6SN7s. There quite a few excellent NOS 6SN7s out there, but the ones that really stood out were the Brimars. They have the best sound stage and they match well with the 6550s. I threw the stock red based Chinese 6SN7s in the trash. (Need I say more?) I use Mullard CV4004s for my 12AX7s.
So, triode (60 watts) or ultra linear mode(90 watts)? The Stereo 90 has a small toggle in back that allows you to switch back and forth between these 2 modes real time. It's very odd, but you can have 2 CDs from the same band and one CD sounds great in triode mode and the other CD sounds better in ultra linear mode. I try both modes with any new CD I buy. Vinyl is different. The amp stays in triode mode, its simply too sweet sounding to change it. Btw I haven’t mentioned analog because I’m in the process of upgrading my TT, cartridge, phono pre and pre-amp. I don’t like commenting on products till I’ve used them for a few months and the “newness” has worn off. I will say that it would be a waste of Stereo 90 if one didn’t have a good analog source. Yes, CDs sound great through the Stereo 90, I’m very pleased with my MF A3.5, but the sound of a good analog source is to die for. This is where the Stereo 90 really shines; triode mode, some good pieces of vinyl, a good MC cartridge...next thing you know its 1 A.M....
I’ve owned my Stereo 90 for 14 months now, and as I stated in the beginning I really hated it at first, these days I’m some what amazed by it, I’m always left with the impression that it sounds better than the last time I listened to it...”did it sound this good last night?...no, I dont think it did...” Do you get bassoon slap from your 60 watt triode amp?no, you don’t do you (well maybe you do)..it amuses me no end.. I wouldn’t call the Stereo 90 a giant killer straight out of the box, however if you’re willing to spend some time and money on tubes and have good clean non current limiting power source.....

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Product Weakness:	I don't like removing the cover to bias the amp, lots of little screws, one always ends up missing
Product Strengths:	A very well built amp thats easy to use. sound quality can be exceptional with the right tube/ speaker combo

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Associated Equipment for this Review:
Amplifier:	Stereo 90
Preamplifier (or None if Integrated):	Rogue Metis...soon to be upgraded
Sources (CDP/Turntable):	Pro-ject 9/with blackbird. MF A3.5
Speakers:	Acoustic Zen Adagios
Cables/Interconnects:	Acoustic Zen/Nordost blue heaven
Music Used (Genre/Selections):	eclectic indeed
Room Size (LxWxH):	16 x 10 x 8
Room Comments/Treatments:	none
Time Period/Length of Audition:	14 months
Other (Power Conditioner etc.):	Richard Gray RGPC 400 Pro
Type of Audition/Review:	Product Owner

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