surprising comparison of tube preamps

I followed up the idea in this thread - what happens when a good headphone amp is used as preamp in a speaker system. I have actually not tried this before in my main system. Or not since way back. So I brought Audiotailor Jade OTL down to the main listening room, disconnected the preamp, and connected Jade instead. The result was quite good, but not on the level of my (much more costly) preamp (Einstein The tube mk2). It would have been a sensation if it sounded better.

So my experience is that inserting a good tube preamp into the amplification chain depends on the quality of the rest of the gain stages in the chain. For example, the Jade easily beats small s-state amps in  active speakers, from my testing so far (low to mid price). But if the other gain stages are in fact of comparable or higher quality than the Jade, the effect can be zero, or reversed.

Note that, in my other systems, testing with the OTL headphone amp as part of the sound chain, the chain has been like this:

Source (DAC) - > Jade - > preamp -> amp.

In my main system, however, I had to connect this way;

Source (phono riaa + preamp) - > Jade - > amp.

I was not able to insert Jade as the first gain stage.

Something is wrong when it is connected as the last gain stage. I tap on a tube in Jade and hear scratching noise in the speakers. So the sound impression, described above, may be misleading. Maybe this isn't a fair playground for Jade. Connecting a headphone amp as the last gain stage, with output to the amps, is not the right way. Even if it works fine as the first gain stage.

@arhgef - I am not suprised at all. I have an OTL headphone amp that I also use as preamp in my office system. Between the DAC and the integrated amp to the speakers. Although one more gain stage is not ideal, the results are clear: The more of the total gain made by the OTL, the better the sound. It might even improve the sound in my main rig, but is not practical to use there (maybe, I should give it a try). I also agree that AR can be a bit lean and analytical, I have other tube gear with more bloom and warmth, which I like (to an extent). I think the great thing about OTL is relative simplicity. So I am sceptical about 'simulations' (but have not heard your example).