At present I have a vintage McIntosh C26 Preamplifier with which I can adjust EITHER the right or left channel for bass, treble, and volume. Are there any modern preamps that can do the same thing? I would like to upgrade.
Richard

Carver C or CT series. Lower numbers before they turned lower mid-fi are better. I have a C-3. Can be had on eBay for under $150 in "one owner, have box and manuals" kind of condition.

Thanks for your help. I'll check them out and then make comparisons.
Richard

Oops, I must have misread the original post.

One bass/treble in stereo. Sorry.