Hi,
I think this thread gives some context for any individual reading it, to judge how much credence he'll put in to my observations. With that said...
The LA4 certainly isn't "lacking" anything. It's just transparent. But I could say it does 'lack' certain things in the sense of comparison to the CJ tube preamp. It's like if you are served your order of blueberry pancakes. It's not "lacking" anything. Unless of course you like
adding whipped cream to your pancakes, then the original order might be seen to be a bit lacking.
The CJ preamp has remained routed through my LA4 all this time, allowing me to switch between the LA4 alone or going through the CJ, with my remote from the comfort of my listening sofa. I'm switching between them all the time because the difference I perceive is so fascinating. Typical of this was listening to some digitally-streamed music last night. One piece had a trumpet way off in the distant right of soundstage, a guitar lightly strummed slightly to the left of that trumpet, the drummer playing a light pattern on the cymbals, occasional snare. Using just the LA4 there was a tremendous sense of "transparency" by which I mean the sense of hearing a super clear view in to the recording, every timbral detail, and since even the most minute bits of reverb were audible, there was a great sense of the recorded acoustic around the instruments. Lovely stuff.
I switched over to the CJ tube preamp and lost a teeny bit of that sense of "transparency" but each instrument seemed to thicken slightly and "solidify." And the tone shifted to a slightly more present "live" timbre. It moved slightly from a "great recording" a more "seeing through the speakers to live instruments playing" sensation. And I love that!
Sometimes when I'm doing these comparisons I'm using the level matched settings I used for the blind test. But otherwise I'm just doing casual listening, switching between the LA4 and CJ, so sometimes I'll switch to the CJ and the sound level will be quieter, or similar, or louder than the LA4. The volume difference doesn't seem to matter - the difference in character I just described seems to always be there. FWIW...
So in terms of the CJ "lacking" and "could I live with just the LA4?"....
The CJ lacks the sense of absolute clarity and nuance of the LA4. I appreciate the LA4 every time I use it. But I also like what the CJ seems to add.
So at this time there's no way I'm giving up either preamp!
But if someone put a squirt-gun to my head demanding me to choose only one, I suspect I'd choose the CJ preamp. A sense of density to the sound is one of my main goals for my system, and it would be very hard to give that up (along with other aspects of the CJ presentation I like).