The LS5 mk1/mk2 have 10 tubes each while the mk3 replaced
the 2 input tubes with FETs and count went to 8. The mk2/mk3
use the 6922 tube while the mk1 uses both the 6922 (6) and
12bh7 (4) tubes. The REF1/REF2 preamps are very closely
based on the LS5mk3 circuit.
The swap of the input tubes for FETs in the mk3 definitely
resulted in less noise over the mk2 version but many feel
(myself included) that the mk3 lost some of the mk2 bloom
and is slightly more sterile but I feel it is still very
very good. I've had an LS5mk2 for almost 9 years now and am
still absolutely in love with it. I have fairly low/medium
sensitivity speakers at 86db so the tube noise floor was
never an issue for me. I could never hear it even right in
front of the speakers. Others with high sensitivity
speakers found the mk2 tube noise floor to be basically a
minor annoynance during silence but rarely if ever an issue
during music. Similar to analog tape hiss. These were the
people that seemed to benefit most from the mk3 upgrade
which lowered the noise floor a bit.
I would HIGHLY recommend the LS5 as it should have no
problem driving your Pass. I vertically biamp two ARC
D400mk2 200wpc solid-state monsters with my Ls5mk2 to great
effect. The tube/SS synergy is just awesome. Anyway, if you
have higher sensitivity speakers you may want to consider
the mk3 version. Otherise I'd go with the mk2.
the 2 input tubes with FETs and count went to 8. The mk2/mk3
use the 6922 tube while the mk1 uses both the 6922 (6) and
12bh7 (4) tubes. The REF1/REF2 preamps are very closely
based on the LS5mk3 circuit.
The swap of the input tubes for FETs in the mk3 definitely
resulted in less noise over the mk2 version but many feel
(myself included) that the mk3 lost some of the mk2 bloom
and is slightly more sterile but I feel it is still very
very good. I've had an LS5mk2 for almost 9 years now and am
still absolutely in love with it. I have fairly low/medium
sensitivity speakers at 86db so the tube noise floor was
never an issue for me. I could never hear it even right in
front of the speakers. Others with high sensitivity
speakers found the mk2 tube noise floor to be basically a
minor annoynance during silence but rarely if ever an issue
during music. Similar to analog tape hiss. These were the
people that seemed to benefit most from the mk3 upgrade
which lowered the noise floor a bit.
I would HIGHLY recommend the LS5 as it should have no
problem driving your Pass. I vertically biamp two ARC
D400mk2 200wpc solid-state monsters with my Ls5mk2 to great
effect. The tube/SS synergy is just awesome. Anyway, if you
have higher sensitivity speakers you may want to consider
the mk3 version. Otherise I'd go with the mk2.