Just because a loudspeaker will work better with a big solid state amplifier doesn't mean it won't work very well with your moderate power tube amp.  I am not familiar with either the loudspeaker you are considering or your current amplifier.  The Technics isn't an easy load, but it's also not difficult load.  It's honestly rated at 4 ohms.  With 4 KT88s per channel your amp should have enough to drive them.  Depending on how loud you listen, your room and your musical taste you could find the Technics/Cayin combo absolutely fabulous.

@onhwy61 The speakers in question are only 83dB 1 Watt/1 meter. Sensitivity-wise this works out to 86dB, but we're talking about a tube amp here and they don't double power as impedance is halved. Instead they cut power in half as impedance is doubled if they are acting as a Voltage source. 

So this is simply impractical and won't work out as you forecast above. 

@mamifero If you like your amp, I'd look for a speaker that is 8 Ohms or more. Your current speakers are 4 Ohms so their actual efficiency is 87dB. Your amp is working hard all the time with that speaker- they are not showing it in its best light. By simply moving to an 8 Ohm speaker that is 90dB your amp will need only make half the power it does now for a given sound pressure level. That will reduce its distortion and it will run cooler as the output section will be more efficient. 

@atmasphere, you basically restated what you said earlier in this thread and it's a very sound argument.  I just don't think you are allowing for individual, subjective taste.  We've both participated in this forum for a long time.  One of the things that has been revealed to me is that not everyone has the same goal(s) in assembling/setting up their systems.  It's not even an accuracy vs. musicality schism in that there's not a solid agreement as to what those terms mean.  (There's actually a lengthy thread trying to define "what if high end".  The responses are quite varied.)  Instead our music reproduction systems are more of a reflection/projection of ourselves as audiophiles.  Just look at the variety of systems people have.  As such our systems can be technically imperfect or non-optimal, yet the listener still is very happy with the sound.  If some people want to pair Magnepans with single ended triode amps, my response is go for it and tell us how it sounds.  You want to place big Wilsons in your 12' x 12' room?  It might not be something I would do, but go ahead an give it a shot.  So while I have an opinion about matching the Technics with the Cayin, I and nobody else in this thread can truly predict whether the the OP won't like the combination.

Let's not get all boring and start agreeing on everything.

@onhwy61 I agree, however for me its really about how it can sound even better and thus be enjoyed more too. Put another way its about getting the most out of your hifi investment. 

Review Technics SB-G90 floorstanding speaker 

''So you have been able to read that this Technics is a big heavy, 3-way bass reflex speaker. So far so good. The nominal impedance is 4 Ohms and the continuous load 100 watts. 200 watts peak. That’s more than enough for many a living room. It takes about 40 watts to get it going. We estimate that a tube won’t go very well, but who knows with a heavier 300B it might work, considering the efficiency is still about 88 dB. That’s not super high, but it’s not low either.'' see review here

Mike

Based on my experience trying to match 86dB speakers with a tube amp, the size of the woofer and controlling that driver have a lot to do with whether a tube amp or SS will work better. The JBL woofers are not that large. If you can demo them, do so. But as you have not purchased the speakers, and if you can't demo them with your amp, I'd look for better synergy on paper.

I ended up with SS. You can see my set up in my profile.

As for power, in a semi-contained listing area that opens to a much larger open plan living space, I'm generally using 10 watts or less p/c and filling the space nicely. Volume range -40dB to -30dB albeit with virtually unlimited headroom.