Tube Phono Preamp ? ? ?

Audio Note RIAA is very nice. Over your budget at 800, MM only.

If you are restricted to a $500 budget, my best suggestion is an interim approach: buy a used Adcom GFP-565 preamp, and save your money until you can afford a much better tube unit. The Adcom 565 has an excellent phono stage (it got outstanding reviews in the audio mags at the time it was being manufactured), as well as a bypass output. A used Adcom GFP-565 preamp usually sells for around $300 here on Audiogon.

Look into a AES PH-1 from www.audioelectronicsupply.com. AES is a division of Cary Audio. They list for $600.00 assembled and $400.00 in kit form. They don't come up for sale that often used, and when they do, they are gone in a few days.