Need recommendation for a preamp.

Have sold both on a retail level for years. My advice?...skip em both and have better sound! Even old Audio Research LS2,LS5, LS7, etc, used sound better with good tubes in em! For $500-$750, you could get much better sound than the ones your describing. Also, if you can find that Cary piece that was around $1200 a couple of years back, that would be the best for your money by far! The ones you mentioned are average at best...don't be suckered in by the "Class A" rating on the Adcom...someone got paid trust me.

If it's the Cary SLP-50 referred to above, it is a very nice little preamp. Since you are interested in passive, you might want to give a Placette Passive linestage a try. I think the used price is still around $900, if you can find one. You should be able to audition a used one and recoup your investment if it's not to your liking. The linestage comes with a remote control that does not adversely affect the sound quality and has three inputs and two outputs standard. They also make a RVC, remote volume control, that is a single in/out and is around $700 used. It is the same volume control as in the linestage and also is remote controlled.
info link

Check out the Eastern Electric MiniMax. I have had Spectral, Hovland, Audible Illusions, passive attenuators, Copland, Audio Research LS1, LS7,...you get the idea. I love the presentation this little gem gives. It's easy for tube rolling. The value this unit gives is simply amazing. Bill O'Connell at the Morningstar Imports has a wealth of knowledge (and a Hovland too) when it comes to tube rolling. I bought mine from Galen Carol Audio in San Antonio. He is an extremely fair person to deal with and a lot of fun to boot. I believe the website is eeaudio.com. Check it out. A lot of fun and fantastic sound for the money.

I have no affiliation with any company mentioned above.

I agree with foreverhifi2000..

I will be honest and state that I have not heard any of the preamps that you mentioned. (Although I had heard older Adcoms, and was never impressed). However, I have had an ARC LS-2 preamp for many years, purchased used also, and it is one of the best, most neutral sounding preamps I have heard. You can probably pick one up for way less than a grand. The only downside, is that you will not get a remote. (The remote version is VERY rate, and VERY expensive!) I purchased this as a stopgap measure figuring I would trade up at some point. Never have yet.

Good Luck in your search.

Roy, I don't know what your source is, but if it has at least 2v output a passive would work fine for you. Your amp is a great match-up for a passive. The Bent audio tvc or the Placette models are the best (used) in your price range and will compete with active pre's costing $1,000's more. I have the Bent Audio passive in my system and went with it over the Placette because I wanted balanced connections on my Krell amp, the Placette is much more money for balanced. They are both very good passive's. You can read reviews for both at the audio asylum forum. Passive's are only great if they match-up well with: source/amp/speakers in your system, mine does in my system. (Sony XA777es-Bent Audio passive-Harmonic Tech. truth-link cables-Krell ksa-250 amp-Vmps super tower/r speaker@91db.) hope this helps.