KT-88 vs. EL34

"I am currently using Canton Karat M70s, woofers facing out. Not too efficient and 6 ohm average. Current amp is SS, a B&K AVR-307 (150w x 7) in two channel analog mode, used for stereo only."

Since you already have the gear, you might as well try a vertical biamp. Remove the jumpers on the back of the speakers and use 2 channels on the amp for each speaker. 4 channels, not 2. It may make a big difference, or not. Results vary.

Thanks for your thoughts, sfall. As it turns out, I had already bi-amped these speakers in the past, more for control than for power. I had used different amplifiers and not all four from the B&K and for the following reason... To use 4 or any more than 2 channels from the B&K, you must be in the digital mode, that is to go through the amp's DSP. Although virtually indistinguishable from 2 channel, I wanted to keep my signal path pure analog which bypasses the DSP altogether.

Also, my listening room is small by most standards and the 150W per channel from the B&K's humongous power supply is an overkill as it is. In fact, to handle the myriad problems a small listening room provides, I use a 31 band equalizer to tailor the sound... particularly the bass bloat from the nearby room corners (and for minor adjustments to the rest of the audio spectrum).

You may be thinking that the Canton Karats are too much speaker for a small room and you'd be right, especially considering the smaller model speakers that are available. However, it's what I have to work with so it is what it is. Thanks again, Andy

You should be able to swap in 6L6 for EL34 as long as you can adjust the bias AND you get the GTB versions as they can work with higher plate voltages AND as long as your amp can work with these tubes in the first place. 

I thought you had a seperate multi channel amp, not a receiver.

I have the newer 3502 model that takes EL34 as well as 6550 types.  Like someone said, one tube type is not necessarily better than the other, just different.  The amp does have more bass heft with the Svetlana 6550 than the new production EL34 and EH 6ca7 tubes I tried.  One exception is the JJ 6CA7.  This is a sweet tube!  Refined and warm with plenty of bass.