Need help picking a preamp.

I'm a long time listener to music and am trying to slowly upgrade to a better quality sound. Looking for a preamp in the 500-$600.00 range but am willing to go to 700-$800.00 range if the extra money would equate to a difference my ears would hear. Do not know which is better (SS or Tube) in my price range and with my setup listed.I assume used in the way to go.(Jazz, Classic Rock, Rock)

Nad C720BEE
Yamaha Av RX-V530
Onkyo disc
PSB Image T65
PSB Image S50
PSB Image C60
Yamaha Sub SW 90
Mapletree tube preamp is awesome little bugger for the money.
Around $800 new.
It will serve you for many,many years and it is a pleasure to listen to.
I know few guys who own this preamp with systems FAR more expensive then yours. Juicy Music Peachtree is also great preamp if you can find it used in your budget. Integrated amp is another option which you can consider.
It might be a little over your budget tho. There is one you might really like up for sell at great price. The seller won't ship but it doesn't hurt to ask - DK Design vs 1 mk ii Integrated amp.

Oh yeah........everything will change the sound.
Speakers and amp is a good starting point and the most important factor to successful system.

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Eastern Electric Mini-Max. No comparison.