best pre-amp new or used for under $500?

Ddan - I ran a pair of B&W 685s with a HSU sub for about 6 months, until I bought the Denon AVR. I used a 15 year old Yamaha integrated, connected the sub to the B speaker terminals, and just used the crossover on the HSU, so no high-pass for the 685s. When I bought the Denon, I tried high-passing them, and was not satisfied until I bi-amped the 685s with the Denon's rear channels. Even then I thought the sound was better running the 685s full range. Now that I have the Rotel to push the 685s, the sound is much better. Still not sure about the Audessey room correction on the Denon - this is why I want to check out a pre-amp with bass management.
Some folks highly recommend tubed pre-amps, like the Anthem Pre 2 L, http://www.audiogon.com/cgi-bin/cls.pl?preatube&1280423801&/Anthem-Pre-2-L--SE-special-edi, doesn't have bass management but does have two sets of pre's, so I can use the crossover on the powered sub...so quality pre or bass management I guess is the dilemma.

Hello. I happened to stumble across this thread, and thought I'd make a suggestion that may be worth considering. How about the purchase of an Oppo BDP-80? Yes, it's a respectable DVD/CD/SACD player. You can connect the Oppo directly to your amp via the left/right output directly into the left/right inputs to your amplifier. The Oppo features its' own volume control, so you totally bypass the use/need for a separate pre-amplifier you'll have full volume control via the Oppo' remote. Depending on the model 'Yamaha' CD changer you're planning to use, you may find that the Oppo proves to be a step 'up' from your 'Yamaha'. You can purchase the BDP-80 for less than the $500 you have in your budget, and, simultaneously add a nice piece of equipment to your setup.

Well, that's how it goes, first I buy, then I check it out....Yah, I just put in an offer for a Nakmichi CA5 MK11, and first thing I read here is that it doesn't sound good. Many years ago, I owned a CA5, and regretted ever selling it. But maybe a mod of some sort will bring the MK11 up to standard.

UPDATE - I now play 2-channel music through the Denon, using the Audessey room correction and the "restorer" set to "HD." The latter is meant to give detail and weight to the high and low frequencies. Using all of these processors isn't really a purist, audiophile way to listen to music, but it beats the hell out of the Denon's "pure direct" mode, and I'm pretty happy for now. I had to play around with speaker placement, listening position, and all of the settings on the Denon, but I have arrived at a fairly good place for 2-channel music. Wouldn't it be something to buy a dedicated pre-amp and new speakers for my basement office, and not get better 2-channel sound quality than my HT rig...? Well that experiment will have to wait until the economy comes back...

Ok, so I got a Nakamichi CA5 instead of a CA5II. Got a question; any ideas about some simple upgrades in the circuitry?