I love the Thiels, although you're pairing speakers that could potentially be described as on the "lean and bright" side (at least that's how I recall hearing them), and an amp that definitely fits that description. You might look to a preamp that could add some warmth, fullness, and flesh to the sound. That's a tall order for under $500.
One such option is the Marsh P2000t (which I used to own many years ago). Or you might consider a preamp from a company such as NAD or Parasound. Or, if you're handy with a soldering iron, consider one of the Bottlehead (vacuum tube) preamp kits to put together.
To be completely honest, though, I'm with jmcgrorgan2 in that I think you should sell the Bryston and use the proceeds plus that $500 to get a really good integrated that mates well with your speakers. I truly think you'll be much happier in the long run at that price point.
Otherwise, if you can save another $500-1000, you'll be able to choose preamps in an entirely different league that will fill out your system much better.
Michael
One such option is the Marsh P2000t (which I used to own many years ago). Or you might consider a preamp from a company such as NAD or Parasound. Or, if you're handy with a soldering iron, consider one of the Bottlehead (vacuum tube) preamp kits to put together.
To be completely honest, though, I'm with jmcgrorgan2 in that I think you should sell the Bryston and use the proceeds plus that $500 to get a really good integrated that mates well with your speakers. I truly think you'll be much happier in the long run at that price point.
Otherwise, if you can save another $500-1000, you'll be able to choose preamps in an entirely different league that will fill out your system much better.
Michael