Tube amp, more low end

I did mention that I only listened to the EL34's for about 5 hrs and put the KT88's back in. I did that because when I was auditioning a demo Octave I only had 3 days and 3 sets of tubes (EL34's - KT88's and 6550's). BTW the tubes belong to Dynaudio and my dealer. I Like them all and was doing the demo without my sub to compare just the amps. The EL34's were light on the bass. Now that I bought the Octave I've decided since the 6550's were on order I was going to listen to each set of tubes for at least 2 weeks before rolling to the next set. The KT88's are the ones in now. It also takes a little time to adjust the sub for the different tubes. Tube rolling is fun - at least for me. Oh yeah I have a Rel B3 sub FWIW.

The ability of a tube amp to control woofers on low impedance (4 Ohm) speakers is mostly a function of the quality of its output transformers and size of its power supplies. Beefy power supplies are not at all cheap, and output transformers of the quality required to really do the job are extremely expensive - they only show up in the very best tube amps. There's no solution other than moving to speakers with a much more benign impedance (or switching to a similarly priced solid-state amp, which of course brings its own set of compromises).

The 3.1s are not
'hard to drive" I've had a pair,
As for good output transformers and poer supplies,the Manley snappers at $4000 retail,do the job extreamly well.And they feature EL34's

The above comment about the Snapper gives me a good example to explain my point about output transformers and power supplies.

The Snapper puts out 100 watts per channel. The CAT JL-1 monoblock tube amps also put out 100 watts per channel. The Snapper, according to its website, has 180 joules of energy storage in its power supply. In contrast, the CAT has 1,000 joules of energy storage. The output transformer alone in each CAT monoblock weighs 55 lbs., the total weight of each monoblock being 192 lbs., with most of the weight being the transformer and power supply. The Snapper weighs 38 lbs., a mere toy by comparison. Top-shelf transformers and power supplies are not only extremely heavy, but are extremely expensive - the CAT amps, for example, retailed for $30,000 ten years ago (the Snapper retails for $4,000). With tube amps, cost and weight are directly correlated and tell you most of what you need to know about quality.

Most tube amps layer space well, tend to be organic-sounding, and have a nice midrange, but with all due respect, they do not, except for the very best ones, control woofers on speakers featuring low impedances in the bass - this is their Achilles heel.

Since you like the sound of the amp you have; you might consider adding the Gallo TR-2 Subwoofer to the mix. You would essentially be bi-amping, with a 250 Watt amp, powering the bass. Much more "live" sounding bottom, than any tubes, or tubed amp(at an equivalent price), would provide.