Preamps in the sub $500 range go quickly. You have to be ready to act quickly if you want to get a good deal.
I see a Rogue Metis in the classifieds right now for $450. This is a well regarded tube preamp that includes a phono section and remote control. It will add some warmth to your SS amp and be a nice foundation to build on. If I were in your shoes I'd jump on it. Live with it for a month and do back-to-back comparisons with your Adcom GTP-500II. That should give you plenty of time to hear the difference. There's a nice review of the Metis at 10 Audio
I see a Rogue Metis in the classifieds right now for $450. This is a well regarded tube preamp that includes a phono section and remote control. It will add some warmth to your SS amp and be a nice foundation to build on. If I were in your shoes I'd jump on it. Live with it for a month and do back-to-back comparisons with your Adcom GTP-500II. That should give you plenty of time to hear the difference. There's a nice review of the Metis at 10 Audio
Will I also need a tube tuner??I think you're referring to biasing, but maybe you literally mean a tuner. FWIW, tube preamps don't need to be biased, but tube amps do. Instructions are usually included with the unit.