Honestly speaking, I think your amp is your
weak link here. Don’t get me wrong, I am
actually a total Krell fanboy. I
absolutely love the Krell analog audio circuit and it’s the best thing since
sliced bread! lol. Your Krell S1500 uses
that specific variant of the Krell discrete Class A input/driver stage. However, like many other Krell devices at
this level, the low voltage power supply for the input/driver stage is SEVERELY
undersized. Even though the amp itself has
enough power to push 300 watts a channel, the input/driver stage dictates the
sonic signature. When the power supply
is undersized for that input stage, the result is a very bright/harsh with thin
body and weak bass. I have done this on
more than one Krell preamp type device where doubling or tripling the power
supply capacitance turned the common yucky Krell signature into something
magical with full body and powerful strong/deep bass. I believe Krell has detuned these lower level
offerings on purpose so that they have a reason to charge insane amounts of
money for their top-end stuff.
Getting something like the Mark Levinson
326s preamp will definitely be somewhat of an improvement over the Yamaha processor,
but you are never going to be work around that problem in the Krell
amplifier. It might even make it worse
because the resolution of the 326s would be much higher than the Yamaha, so you
could potentially be revealing the Krell flaws even more so.
You could get an integrated amp if you
wanted, but it is not going to sound as good as a really nice preamp/amp
combination. Some of the upper level
Hegel integrateds come to mind. The Hegel
H360 would be a great choice and it would beat the crap out of the Krell S1500
in terms of sound quality. An integrated can be a good solution if cost is a factor.
That being
said, getting a ML 326s and pairing it with something like a Parasound A21 or
the Parasound JC1 monoblocks would sound absolutely stunning!!! Another excellent preamp is the Krell Illusion
or Krell Phantom I/II. DO NOT get the
Phantom III because it suffers from the undersized power supply (like I
discussed above). There’s a Krell
Illusion II on audiogon now for $3400.
If you are intending on ultimately getting separate
preamp and amplifiers, I would choose to upgrade the amplifier first in your situation.