Quality used amplifier needed

I am in the process of upgrading from an Adcom 555mkII that has been modified. My friend has a Threshold S300mkII that I have heard on my system and it sounds fantastic. Are there any other used amp I should look at in the under $2000 range. My speakers are 4 ohms and I feel I need an amp that put out 300 watts at 4 ohms and is also able to deliver high current. Thanks, CS
I would consider McCormack DNA 1 Check out review in stereophile. I have owned one for 3 years and love it
See my ad for Kinergetics KBA 75. I own a hi-end company www.audiotweakers.com. This amp has been in my personal stash for 4-5 years. With the right complimentary equipment it competes with anything. Retail $1995, plus $300 power supply mod- sell $995 OBM. Pure Class A doubles down to 300 w@2 ohms. Weighs 50 pounds. FIrst class all the way.
Try to get your hands on a Aragon amp. I own a 4004 and while it is an older unit it will drive ANYTHING. Very relialble amp. Enjoy the music.
to improve your 555II, try something like an arc preamp. i substituted a sp3a-1 for the 565 and the whole thing opened up. dynamics espewcially. tubes in front of adcoms are highly recommended as far as im concerned. my friend use a counterpoint pre and the results are very nice, and this is with ml requests. ive been warned that adcoms are too bright for MLs but that is crap. borrow an arc if you can, you may not buy another amp......
The Krell KAV-250a is the clear winner by a WIDE margin here!! 500 watts rms into 4 ohms, per channel. VERY HIGH CURRENT, so build a dedicated 30 amp circuit...Around $2000 used.
MUSE SIGNATURE SERIES II MODEL 175 & MODEL 300 Monoblocks would be excellent choice for your application. The 300's output: 300W, 8 ohms, 500W, 4 ohm. with Output Current Capability 70A Max. The 300's were designed to cope with the requirements of modern low efficiency loudspeakers with their demand for large output voltage swings. The MUSE 175's Output: 175W, 8 ohms - 325W, 4 ohms - 550W, 2ohms. with Output Current Capability 90A Max. Frequency Response for both: -3db at 13Hz and 250 kHz. The 175's have been optimized for low to very low impedance loads and can handle the most difficult loudspeakers. For any system that dictates unshakable current capability and absolute load stability, the 175 or 300 Mono Blocks are up there with the best, WITH NO EXCEPTIONS. Both list in the $3,500 - $4,000 range, probably out there somewhere in the used market in your price range.