VTL 6.5 vs VTL 7.5

How much difference is there between these two preamps? Is the 7.5 quite a bit better sonicially than the 6.5?
Very few differences

(1) Output coupling caps are smaller on the 6.5
(2) 6.5 uses unshielded relays; 7.5’s are shielded
(3) Of course the 7.5’s power supply is physically separate.

Luke Manley claims that the 6.5 delivers 85% or more of the 7.5 sonics – very, very close.
I am trying the 6.5 now...latest version...might consider the 7.5 mkII...is it worth the difference....I have put some NOS tubes....seem to make a significant difference...clear top RCA...also some GE 6189W mil spec....and some Sylvania tubes...working my way thru them....any suggestions?

I auditioned both of these preamps and went with the 6.5 MK II. There simply was not even close to a $5k difference in the sonics of the two. Maybe if you had some super revealing stuff downstream, you could talk yourself into the justification of the extra money. In my case, I used the savings to buy interconnects and source material. The 7.5 has a bit of additional slam, but it was subtle, at best in my experience. Re. using nos tubes, VTL ships the 6.5 with NOS GE tubes. I assume they do the same with the 7.5, at least in the audio chasis. I experimented with some NOS Mullard/Blackburn tubes which I found to be very sweet, but perhaps, a bit soft. I've now replaced the Mullards with some NOS GE Broadcast grade tubes that make the unit really sparkle!