Kaiju or Stereomour?

[pplater]

I suspect that this question has been asked more than once and if so I apologise for raising it again.

I recently completed the Moreplay pre-amplifier which I built as stock. I’m currently using it with a small Line Magnetic amp but they are ill-matched (although the LM is just fine standalone). I would like to put a Bottlehead amp after the Moreplay but cannot discern whether I should use the Kaiju or the Stereomour II.  The price difference and build difficulty are irrelevant considerations; I would be grateful to know what contributors would recommend, and why?

Other things you may need to know:
•   Sources include Tidal through Roon, CD transport and turntable with mc cartridge, presently through an Esoteric phono stage.
•   Speakers will principally be Falcon Acoustics LS3/5A (sensitivity 83dB, nominal impedance 15 Ohms) but Harbeth M30.2 (sensitivity 86.5dB, nominal impedance 8 Ohms) will get a workout and there’s a pair of Klipsch RP600M (efficiency 96dB, ‘8 Ohm compatible’) in the background. I get that they’re not the best selection for lesser powered tube amps but they also serve other components.
•   Listening room is a good size, but not huge. I don’t need ‘stadium volume’ but a satisfying range for the odd outburst would be welcome.
•   Music preferences are classical and jazz; cello; female vocal.

With thanks in advance for your thoughts.

Cheers,
pplater.

[Deke609]

I can't speak to how satisfyingly loud/full the amps will play with your speakers - other than to suggest that with your lower sensitivity speakers, you might want to consider bi-amping down the road - i..e., 2 Kaijus. But I'm sure PJ or someone who knows PJ's formula for desired wattage for speaker sensitivity for listening distance will opine on this.

But I do have some experience with both the Stereomour II and the Kaiju - and I will wholeheartedly and unreservedly recommend the Kaiju. It just sounds "clearly better" to my ears. I could try to express this "better" in all kinds of audiophile language - but I think "clearly better" captures it. I'm sure there are earlier posts from me after I got the Kaiju that use tons of audiophile type lingo to sing the Kaiju's deserved praises.

What makes it better? For one, the Kaiju has superior iron - both plate choke and output transformer. I know this b/c I've actually installed the Kaiju iron in a Stereomour and the result was a big improvement over the fully upgraded Stereomour II sound (which itself is very good, but the Kaiju is on a different level IMHO). But even with the Kaiju iron, the SII still doesn't match the Kaiju. I suspect that there is something special about the 5670 driver in the Kaiju and perhaps the regulated DC filament supply of the upgraded Kaiju versus the unregulated DC filament supply of the upgraded SII - buy you may not need/want the DC filament supply with your speakers.

Another consideration: if you might ever be inclined to do some "tweaking" (e.g., trying different boutique or Russian caps), the Kaiju has a lot more room under the hood than the SII. Once fully upgraded, the SII is literally "jampacked" with components.

I'll also add that the new MonoMours are another option to consider. They use the same iron and 5670 driver as the Kaiju, but the 2A3 output tube of the Stereomour II. And can be modded to use 45 tubes. But given your speaker complement, I'd be leaning towards te higher output power of the 300B tube.

cheers, Derek

[jjvornov]

Having built the Stereomour II, the Kaiju and the MonAmour amps, I can say that each one has a different personality.

But the biggest difference is between a 2A3 amp and 300B. To me, the 2A3's have a bit more personality and respond much more to tube changes- with a range of vintage NOS and new manufactured tubes to choose. Especially as designed by the BH team, the Kaiju is really clean, linear and extended and I haven't found that switching output tubes has as much effect as the 2A3 amps.

I have both the big amps in my system and switch between them as I like, but the MonAmours are definitely used more with their more present, you are there sound even if the Kaiju is a bit more accurate.

[Karl5150]

The SII is integrated so the Moreplay would be redundant, unless, as I understand it, you needed more source gain.
Never having built BHs TotL amps, I can't speak to the differences, but with the higher output 2A3s available for the MonAmours, power consideration would likely be a wash.
Karl

[Doc B.]

I'd build a Kaiju for those speakers. The power and the tonal character will complement them. And it works great with a Moreplay.

[Paul Joppa]

...
•   Speakers will principally be Falcon Acoustics LS3/5A (sensitivity 83dB, nominal impedance 15 Ohms) but Harbeth M30.2 (sensitivity 86.5dB, nominal impedance 8 Ohms) will get a workout and there’s a pair of Klipsch RP600M (efficiency 96dB, ‘8 Ohm compatible’) in the background. I get that they’re not the best selection for lesser powered tube amps but they also serve other components.
...

For fully satisfactory loudness (I've often used the phrase "most audiophiles, most of the time") my estimate is a peak loudness of 102dB each channel. That means 80 watts for 83dB, 32 watts for 87dB, 4 watts for 96dB sensitivity speakers.

For SET amps, the graceful overload capability allows as little as 1/4 of that power to work well for many people, so 20 watts at 83dB, 8 watts for 87dB, or 1 watt for 96dB sensitivity.

There is a huge variation of personal preferences, both loudness and musical choice - I am myself satisfied for most uses with 2 watts into 87dB speakers. Fine for the Bach cello suites (I was in my youth a cellist), but when I put on a Mahler symphony for serious listening, I want a lot more. On the other end, a few people seem to feel the need of reproducing the experience of a rock concert, which can take 10 times the power!

That's my somewhat ambiguous take on the subject, for what it's worth. The LS3/5, lovely as it is, is not well suited to SET amps except for small-scale works like chamber music.

[Jamier]

I think that PJ is right about the pairing of SETs with the Falcons or the Harbeths. But, you mentioned that you have RP-600s. That speaker has a claimed 96 dB rating. It also has a hybrid ceramic woofer which can sound very edgy. All of those ceramic-hybrid woofers have that edge, my experience with that was with a pair of Acoustic-Zen Adagios. I couldn’t last five minutes with those paired with a SS amp, but when used with a 300B amp it was a whole different story. The lush tone of the 300Bs made those speakers come to life, sounding much more relaxed but still with great detail. One Kaiju and those 600s should give the result you’re looking for, in a medium sized room.

Jamie

[pplater]

I'd just like to express my great appreciation for all of the replies to this thread (so far). Every one has contributed valuable insight; I am grateful to you all for taking the trouble to respond as you have.

Cheers,
pplater.

[johnsonad]

These are both great sounding amps but the Kaiju will have more power to drive your speakers.  I'm a 300B fanboy and recently built a Kaiju.  If you want more power down the road, you can build a second Kaiju and run them strapped, one Kaiju per speaker.  The Kaiju is a straight forward build with plenty of room under the chassis to mod later if you're interested in monster capacitors and such.