Preamp upgrade

I’m immediately drawn to the Audible Illusions 3B in your list. I auditioned it MANY moons ago and absolutely enjoyed the experience. For reference, it fronted a CAL Delta (anyone remember them?) feeding a modest Exposure stereo amp which drove a pair of Dunlavy IVs, so a very close match to your system context.

Being so long ago, I can’t remember specifics, but do remember liquid presentation, even when driving the Dunlavys. I couldn’t pony up the Benjamins back then for it, so I had to "settle" for a McCormark TLC-1, which I stayed with until I had to integrate my stereo system with the HT. I always do remember fondly hearing the 3B, I had to give up my seat after a time limit - there was a short line outside the auditioning room. I did obtain a set of Dunlavy SC-III.As, though.

I experimented with a number of preamps over the last fifty years and have kept coming back to Audio Research. While there was a bit of variation with the introduction of the ARC Ref 1 & 2 preamp. Once that was ironed out, in general the sound improves with each generation of preamp. The current models are spectacular… LS28SE… which a friend of mine purchased about a year ago and the Reference 6SE which I own.

ARC continues to carefully walk the line of musical first… not loosing the natural midrange bloom, then adding detail and dynamics while lowering the noise floor. Worth the marginal improvement, to me, absolutely. There are a few folks that liked the warmth… with somewhat lower detail of some older ones. But for most tastes… current are just plain better.

Thanks for the responses. I would say the audible illusions was recommended to me many years ago when I bought the Ls-7. At that time I was looking at a 3a. The 3b is still a contender. I do actually appreciate the warmth and bloom of the ls7. I think the true exercise here is what is the degree of audible “improvement” from the Ls7 that cost 550.00 to any of the mentioned tube preamps that will cost 3K to 6K on the used market which equates to 6-12 times more cash spent for what percentage of true performance increase.  I’ve a it plain better at that cost? 

@jelliott78 the increase in performance when upgrading a preamp depends on how good the upstream and downstream components are. LS7 was an OK preamp when it was new but there’s a reason why ARC made several more models up from it. The Ref 3 will crush it if there’s synergy with the rest of the system.
Matching preamp to the rest of the system is never a plug and play type deal unless you’re buying same brand/line components.

I would say my upstream and downstream components are quite good.I totally understand that there isn’t any plug and play options in reward tomorrow choices. However the question is there going to be reasonable gains for spending 6-12 times what I paid for the LS7. Define crush? Is that a 5 percent 10 percent gain crease for the money?