Sounds like you're asking for a multichannel amp with killer bass, and without the cold sound of many traditional high-power amps.
I have used the Nuforce MCH-2C7, also available in 3, and 5 channels (which I can switch down to stereo, using the remote, for my serious 2 channel listening).
I find the NuForce MCH to have the qualities you are asking for: tight, deep well controlled bass, with warm tonality... and you can add world-class dimensionality.
The NuForce multichannels have an impressively beefy chassis, but offer the same modules and sound quality as their much awarded mono amps.
I don't see any used here, today, but since their products are close to your price range new, and you can try them for 30 days free, I suggest contacting them directly.
I don't think you will be disappointed.
I have used the Nuforce MCH-2C7, also available in 3, and 5 channels (which I can switch down to stereo, using the remote, for my serious 2 channel listening).
I find the NuForce MCH to have the qualities you are asking for: tight, deep well controlled bass, with warm tonality... and you can add world-class dimensionality.
The NuForce multichannels have an impressively beefy chassis, but offer the same modules and sound quality as their much awarded mono amps.
I don't see any used here, today, but since their products are close to your price range new, and you can try them for 30 days free, I suggest contacting them directly.
I don't think you will be disappointed.