The Hersey"s are 1985 by serial number .
I have had them for about 1.5 years.
i have not open the back yet to check drivers models. They where one owner he said they were MK 1
I can run amps independently or all 3 at the same time.
the input source is the DAC which goes to the EQ.8 then the amps are Daisy chained use RCA Leads that have a Y connector at the terminator end.
So the amps I found those for $450 the 1st one delevoped a hum . at 6 months I had the Amazon warrenty . they sent me a replacement amp .
i asked for a voucher to return the bad amp.
Amazon could not find Company that shipped it to me.
They told me to Keep it.
I did not have anything to lose so opened it up.
and found 3 bad soldier joints.
9 months later the company released a amp with bias adjustments.
so note if you look into Tube amps . You want Bias adjustments. You will want a solid state amp and speaker with a sub out.
tube amps. you will want a DAC you will want a Equalizer there are no tonal controls on tube amps.
if you and decent bass response you will have go with Mactosh or add a solid state support system.
it has been a learn journey getting my system were I want it.
(CHASING THE GOLDEN NOTES OF SOUND)