The chip in the 4,5 and 7 definitely do hi-rez as well as PCM so no limitations there. Only the 6 is limited to PCM due to the the vintage of the chip.
The main difference between the 4 and 5 is the fact the latter is dual mono. The 7 is a completely different beast, dual mono as well but employs direct heated triodes.
I'm the co-distributor and we just debuted the 7 for the first time at CES in Vegas. It's supremely musical to anything i've heard. The delicacy and soul of music must be heard to believed. Forthcoming pro reviews are already in the works.
The main difference between the 4 and 5 is the fact the latter is dual mono. The 7 is a completely different beast, dual mono as well but employs direct heated triodes.
I'm the co-distributor and we just debuted the 7 for the first time at CES in Vegas. It's supremely musical to anything i've heard. The delicacy and soul of music must be heard to believed. Forthcoming pro reviews are already in the works.

