Suggested upgrade paths

The Eversolo DMP A8 has a pretty good DAC, and streamer.  You could try one of those for an in-home audition.  This DAC is completely different from the A6's.

I have an A8 in my 2nd system with an Elekit 8600 and Harbeth P3ESR speakers and it is rather nice.

There is also an even better A10.

If you bought the A8 you could be out-of-pocket only about $1,500 as there is a market for a used A6s at about $500.

OP

@nucleardog61 

When you wrote that as the volume increases, the Treble starts to sound shrill. I have encountered this, and the culprit is that the AMP cannot give the power to the speakers. when we replace the amp, problem solved. I have owned a couple of Rotel Power amps, and they do sound good, but they all seemed to run out of steam as the volume comes up. even driving horn speakers

Being cost sensitive, I suggest used. a Used Pass or Luxman may be the fix. 

I have seen good reviews of the Litton so that is ok for now. I truly suggest a powered sub like the RELs and SVS line. BUT I truly believe that the possible culprit is that your amp is running out of steam as you punch in the power

@joeycastillo that was my 1st thought to.. especially when he mentioned he didn't think the bass was punchy or good with volume up either. Like when you are really taxing an amp & the bass actually starts getting quieter as you turn up the volume. Clipping the amp would cause high frequency distortion. 

I assumed that the amp couldn't be the issue as I believe it's rated at 200 watts x 2. I've had a couple Rotel amps in the 90's & a 1582mkii I picked up awhile ago. I never noticed an issue but I probably never pushed them hard. Maybe the Super Lintons are tougher to drive or that amp just doesn't have the guts to provide it's specified wattage. 

Your assessment makes more sense but that's a shame if a 400 watt amp can't push a pair of bookshelves to loud volumes. 

@mattw73 

I agree with you as I believe that the amp being 200W has the drive capability. Not owning the Litton's BUT owning a few Rotel, I can only speculate at the power amp as a possible culprit. My Experience with the Rotels (Lacking power) was when I played large ensembles and when music that is being played has a lot of drums and low frequency Organ music, I did notice that vocals and treble became shrill BUT when I lower the volume, the shrillness disappears. The speakers I notice this anomaly where on LRS and ATC speakers. However, it does not seem to be apparent on B&W 

I stumble into the Fix when I got my Pass. All of the above speakers had NOT manifested the shrillness at all. it just plays LOUD and Clear. (a bit of disclosure, I don't listen loud unless I am doing some testing)

That is why I posted my observations on this thread. The OP may benefit on what I have encountered. a Sub is a good add on, so it makes the music bigger, fuller not needing to raise the volume, but it's not the fix

I also assume that the OP has the correct Power sources to supply the amps (good size power cords and clean power outlets) as that too can restrict power to the amps

@joeycastillo yeah after you shared your similar experiences I don't doubt that thé amp is the weak link in this situation. I think you hit the nail on the head. I was just initially surprised due to specs & their decent reputation. But that really means nothing lol.