Sleeper preamps: $500 new/used

Sometimes you can find a used MFA Magus for around $500-$600.

Phono stage is excellent, with 46db gain, plug-in resistor loadable.
Linestage is very good, with 20db gain.

Phono stage has 1 12AX7 per channel.
Line input has 1 12AT7.
Main output is 1 6922.

Features separate power supply on captured umbilical.
Has CD input and full tape loop.
Easily modded, and responds well to mods, such as re-capping, re-wiring, and re-jacking. Uses Alps pots, which are upgradable to Goldpoint stepped attenuators if desired.

One of the best values for the money, and has good reliablity.

There are 3 versions Magus A,B, and C. I like the C, but I've heard of several people who prefer the older A or B.

I bought mine used with many mods and upgrades for $900.

It's a Bruce Moore design, with factory support from Bob Bergner at RB Audio(current Bruce Moore distributor).

Other possibilities are Counterpoint SA-3 or SA-5, and possibly an ARC SP-6(likely more than your budget), or an older Audible Illusions Modulus preamp.

NAC 42, due to the DIN connectors, and required external power supply(SNAPS or Hi-Cap), the old Naim preamps are probably more difficult to use with other brands of amps. They don't have their own internal power supply, so you must have the outboard supply(or use a Naim amp).

Also the phono boards are known as "N"(MM) or "S"(MC) and are little cards you can swap out. If the preamp is listed as a NAC42S, then it has the "S" cards.

They would be the obvious choice if you plan to use an older Naim amp, like a NAP 250,160, or 110.

Phono section "S" has high overload margins, and handles low output MC cartridges.

I had a Naim NAC 42S with Hi-Cap supply for about 11 years, along with a Naim amp.
Not bad for SS, but my modded MFA Magus C murders it, IMO.
You know, the whole tubes vs SS thing.