Keith,
That's a very good question. The VS115 is a completely new fully differential circuit based very closely on the more expensive REF110 ($10K). Sonically it is much more similar to the REF110 than the VS110.
The VS110 was simply an enlarged version of ARC's entry level VS55. Both were less sophisticated unbalanced circuits built to reach ARC's most affordable price points. The sound of the VS55/VS110 is very nice and musical but not as high resolution or as good at the frequency extremes as other more expensive ARC amps like the VT100mkIII.
Looking closely and comparing the VS115 to the REF110, you can see where the compromises were made to get the VS115 down to $6500. The open chassis with no thick faceplate is much less expensive as are the binding posts on the back. The power supply filter cap bank is a little smaller with 8 of the 470uF electrolytics instead of 12. Finally, the critical output coupling caps are much less expensive than the $100+ a piece Stealthcaps used in the REF110.
ARC's goal was to get 85% of the REF110's sound out of the new VS115 and based on my side-by-side comparisons, I think they have done at least that. I just bought a VS115 for myself.
That's a very good question. The VS115 is a completely new fully differential circuit based very closely on the more expensive REF110 ($10K). Sonically it is much more similar to the REF110 than the VS110.
The VS110 was simply an enlarged version of ARC's entry level VS55. Both were less sophisticated unbalanced circuits built to reach ARC's most affordable price points. The sound of the VS55/VS110 is very nice and musical but not as high resolution or as good at the frequency extremes as other more expensive ARC amps like the VT100mkIII.
Looking closely and comparing the VS115 to the REF110, you can see where the compromises were made to get the VS115 down to $6500. The open chassis with no thick faceplate is much less expensive as are the binding posts on the back. The power supply filter cap bank is a little smaller with 8 of the 470uF electrolytics instead of 12. Finally, the critical output coupling caps are much less expensive than the $100+ a piece Stealthcaps used in the REF110.
ARC's goal was to get 85% of the REF110's sound out of the new VS115 and based on my side-by-side comparisons, I think they have done at least that. I just bought a VS115 for myself.