To DAC or not to DAC ?

+1 @ghdprentice 

I might be inclined to skip the DAC and get a preamp that matches the amp and speaker quality. As has been said, you have 2 really good pieces which are being held back from their ability to produce very good sound imo. 

Tubes will make a difference. But the don't generally make a dramatic imnprovement.

@fullers

Yes. I’m not familiar with the McIntosh preamp but I suspect it is a worthy upgrade.. I am partial to Conrad Johnson preamp myself. You may want to consider this one along with the McIntosh and choose the appropriate one for your needs.

BTW I am not affiliated with the seller in any way

Good call @audiotroy 

Just be aware that often those recommending you flip your gear to what they have now will have totally different gear in a year or two and be just as hardily recommending that gear then.

My amp was bought last year. Prior to that I had an amp for 12 yrs. The preamp was bought 2-3 yrs ago. Prior to that I had another CJ preamp for 15 yrs. I've had my speakers for 18-20 yrs. You should not speak in generalities about that which you don't know. I love the music, NOT the gear, though it is a tool to listen to the music and therefore important