Disappointment with Pass Labs - I'm looking for something else

Hello, I am new to this forum and my mother tongue is not English, so please forgive me if I make mistakes as I use a translator.

I recently bought an XA30.8 and an XP12. I was very happy but as time went by I began to not feel comfortable with the sound.
After doing many tests, I find that the XA30.8 sounds very very sweet but actually too much. I find it to be a loosely defined amp, somewhat muddy and lacks a lot of air and grip. The soundstage is very closed.

The XP-12 is the worst of the two. It is a previous that removes a lot of resolution and information, without transient attacks and sunken mid frequencies. Instead it brings warmth.

Has anyone of you found the same?

If you ask me, I have a Klipsch Cornwall and a dCS BArtok.

Now I want a capable amp, forceful, something warm, decisive, airy and with a great soundstage.

At first I thought of changing my XA30.8 for X250.8, and changing the XP-12 for a second-hand Audio Research Ref5. I am afraid of this change and continue with Pass, since I can go back to the same thing a bit.

On the other hand I have thought of going for a Luxman 900 combo, since it has very good reviews and from what I have read it could be the winning ticket.
I recently tried a Xp12 and also found it tame, polite, un-dynamic.  I paired it with my Pass XA25 and Cornwalls.  I just got a LTA MZ3 and boy what a difference! Much more dynamic, engaging, possibly more resolving, better bass.  My opinion would be to try new preamp first, I’ve never heard anyone describe the 30.8 like you did.  I didn’t think the Cornwalls could be tame and in-dynamic, but that what the xp12 did, I was shocked.  Of course my system, my room, my ears.
I am a long time Pass fan. I bought a Threshold 250 watt amp in ~ 1980 A T2 preamp shortly thereafter, then a Pass x350 for 15 years. He does outstanding amp design and good preamps (not to my taste now). 
But from what you are saying about your tastes the Audio research preamp sounds like a great match. Your tastes sound like mine.  I owned a Audio Research REF 5SE for years, I now have a REF 6SE. The REF / Pass 350s is a good combination and would be better than the amp you have now.The speakers unfortunately are probably the real problem. The amp could be great depending on speakers. Not sure what your price range is, but you need some accurate high end speakers, B&W, Wilson, Sonus Faber, the choices are endless, I would stay mainstream then there are lots of reviews. Over the last 50 years I migrated from a mixture of components to All Audio Research Components and Sonus Faber Amati Traditional speakers, and an Aurender WE20se streamer. 
After reading my rambling post. I think my recommendation would be to get a set of high-end speakers... then assess your system sound. Put some serious effort into finding speakers to fit your musical taste. What music do you like? If it is punch dominated then B&W is a good choice. If you really like imaging maybe Wilson. If highly varied, with classical and acoustic then Sonos Faber...I recommend whole heartedly Olympica or higher.
So many recommendations

@opm, que genero de música escuchas normalmente, yo por ejemplo jazz, blues, rock, Clásico y eso, lo más difícil en mi opinión es reproducir el rock, Por la dinámica y porque las grabaciones originales son normalmente no son las mejores.
Con que alimentas la Bartok? Con CDs? O música en ficheros?

Yo tengo Klipsch P37F y otros con cornetas AudioKinesis Azels, y he tenido bastantes equipos de tubos y de estado sólido, quizás te puedo ayudar a que depures las respuestas.
While it is true that tubes sound good with Klipsch, so does many solid state amps as well. Midfi, the slightly.warm sound of B&K does the trick, Higher end SS Conrad Johnson solid state sounds delicious. Mcormack amps nice! Don't use the High Definition Audio Research SS amps, a waste of time and money, too bright!  I like the high sensitivity of Klipsch because it don't take a lot of power to get em going plus they are revealing of all the fine details and its like being in a front row seat at a concert.