Yes, a well designed one with decent components sounds better than virtually all class a and b amplifiers. Not to everyones taste, but sound more natural and effortless in the way they produce music. Many other amps produce noise in comparison.
You must audition though, and make sure you visit a good dealer....speaker matching is extremely important with valve amps.
The main advantage with the old valve amps was that they had power supplies that could handle sudden surges. I'm not sure if that applies to "modern" versions of them. However, you will still get the noise that is inherent in all valved amplifiers.
Would I swap my Yamaha RXV-1500 for a valved version if it were available ?
Valve amps are musical, and almost any one will blow away your Rotel power amp. Main difference: Not as bright, better midrange bringing out the vocals and instruments, tighter bass. I recommend the Prima Luna Prologue 1 as an amp with NO audible noise, but some of the cheap Chinese amps are really well designed and will surprise most people who think cheap cannot be good.
The Ella is quite a nice amp. Make sure you get speakers of at least 88/89dB efficiency.
Oh, and watching some of the posts on this site, be careful about swapping power tubes. Small signal tubes are OK, but power tubes in fixed bias amps always need re-biasing when you change them.
Also, matched pairs are not needed except in esoteric zero feedback designs where the "natural" gain of the valve is harnessed. The ONLY thing matching will do is ensure the "natural" gain is close.
Must admit I hadnt seen this old thread until today,and couldnt help noticing a few things that arent quite right.
The point about Class A/B amps....valve amps are usually operated in Class A,and a good number of the high-end ones as single ended Class A,and there are as many poorly designed valve amps,irrespective of output stage topology as there are S/S amps.
Speaker matching is essential with SETs,but less so with most others,except with respect to sensitivity and power output.
Another useful point is that most valve amps are a lot more load tolerant than many S/S amps.
A valve amp's ability to produce good,deep,and well controlled bass depends not only on the output impedance,but also on the transformer,which if improperly designed,or with a core too small,will result in sloppy,ill-defined bass with poor extension....this usually equals cost.
Larger,better quality valves as such have rather less to do with it,although using large,high output devices will of course raise the power output accordingly,but will not guarantee decent bass.
Much of the recent crop of modern valves(KT66/KT88/300B's etc)are of very good quality,and very well constructed,although there are still a few horrors around
There is no doubt that overall noise levels in valve amps tend to be higher than with S/S amps,but a well designed one will have a noise floor well below anything you'll hear.
The final point about matched pairs...with respect to zero feedback designs...a lot of these will also be single ended designs,and often using a single output device,where matching becomes irrelevant.
Once again,though,in a parallel SET amp,the output devices should be as closely matched as possible.
Matching does minimise fiddling around with bias levels,and does also ensure that all of the electrical parameters for the valves are,as you said,as close as possible
Had a lot of very good press,as have quite a few of the Chinese offerings recently,as you said also....the build quality has dramatically improved over the last few yrs,and it's pretty clear now what the Chinese intend to do with the market,having pretty much cornered the cheaper end of the valve amp market,and now going for the S/S and CD markets also.