McIntosh C-28 preamp in question

I have a c-28 solid state preamp using it on my mc-2500, and my mc-7270. I seem to be quite disappointed with the sound quality of it. It just doesn’t sound clean and clear as a MAC should. Even with the bass trim turned down, the musical clarity of the bass + treble tones etc. just isn’t as defined as I thought they would. It just sounds mushy, noisy, boomy and tasteless. I own several other MAC pieces, but I’d just like to know if this particular preamp is a reputable pre, or should I just get rid of it and try something else in its place?.
Anyone who’s tried this pre please let me know. Maybe one of the other MAC would fare best. Please help me. Thanks y’all!
 
Never buy a component that you have not tried in your own system, unless you can return it for a full refund.
Many preamps have serious shortcomings, even more expensive ones.
And older ones may need extensive restoration before they perform as they originally did (and that may not be very well).