Audio research and krell

Well, that is one of the craziest things I have heard, not with tubes. I understand the Krell thing… many years ago. A friend of mine has an old Krell. There are lots of other really good options given your system. Your speakers are pretty inefficient… what is your budget? My first thought is a Audio Research Reference 160m or s. I think This would be an amazing combo. I used to have an ARC5se… before I upgraded to the 6SE. What kind of music and budget?

+1 @ghdprentice 

the krell downstream has no idea if the preamp plugged into it has tubes in it or not...

There was a certain BAT tube preamp that had a problem and was putting out DC into amps. I've been running a tube preamp into a krell ksa300s for about 5 years now with no problems.

Ok that's kinda how I felt I  checked for dc voltage on the out puts on both single ended and rear. 4 mv to start and after about 30 seconds nothing. I listen to just about everything I have an opportunity to get a pair of krell 450 mcx but not sure that what I want 

AFAIK, Krell is DC coupled. If your preamp puts out any DC at all it can cause a problem. The solution is really simple, put a cap in series. 2 to 4uF should do.  Get as fancy as you'd like. :)

I run a BAT VK51SE into a Krell FPB-300 for years and have never had an issue. FWIW, the Krell outperforms my previously owned Lamm hybrid monoblocks, especially in the bass performance feeding low efficiency, hard-to-drive  electrostatics.  Cheers,

Spencer

Some Krell amps actually had an internal jumper to add a capacitor to the circuit when using tube pres to avoid DC issues.

@unsound You're correct. The FBP-300 has this. I forgot to mention that. Good callout! Cheers,

Spencer

I believe krell added that jumper during the production of the ksa 250, because a certain model BAT preamp was causing DC issues, not all BAT models were a problem just one model if I remember right.

Yes that's correct I spoke to krell today the protection started on the fpb amps 

You can use your Ref 5SE into any Krell amplifier ever made.

Many years ago Krell said they would not warrant their amps when used with tube preamps because too many tube preamps did not have auto mute circuits (you had to have it manually muted on turn-on) and too many could output DC--which could blow up the amp. (Counterpoint, Melos, Audible Illusions, Paragon...) Even then, Krell would warrant their amps when used with ARC preamps because they were safe.

Your 5SE has coupling caps that will not pass DC, so you are fine.

Your 300S is over 25 years old and it is likely that some of the capacitors are showing their age. If the two halves are not discharging evenly when you turn it off then you will get some funny noises. If you turn off the 300S (with the 5SE muted) and you hear noise through the speakers, it's coming from the amp.

If you like the idea of older and big powerful amps, on US Audio Mart, there is a fella in the Santa Clara area (CA) selling a pair of Audio Research Ref 600 Mk IIIs in a black finish for $10,000 bucks I think.  That would probably mate up nicely to your ARC 5SE preamp.  When it comes to audio gear, if I can't move it myself, I don't buy it.  I seem to remember the Ref 600s weigh in around 170 or 180 pounds.  I bet those amps sound glorious though...