I own a Krell SACS Standard mk3. When I was looking I even
called Krell and they told me the same as what all the
online posts have said. The mk1 and mk2 have a Bad
transport that will fail and it's just a matter of time.
To Krell's defense everyone was using this transport at
the time since it was once considered the best. Many
other highend Manufactures dealt with the same mess.
Krell lost hoards of money switching out transports under
warranty. Only the mk3 units or units that were repaired
by Krell to have the mk3 transport will be reliable.
The Tell-Tail sign is that if it has a blue display then
it's got the new transport. If it's got a red display
then it's days of life are limited. This is why mk3s
sell for $3000 (or more) used while mk1s/mk2s sell for
$1500 (or less) used.