I recently bought a UFO25 that Groovy was selling for his brother. The amp is beautiful like you said, more striking in person. I was previously using a UFO with 25th mods and really liked it, I thought the transition would be a simple one, nope! I also bought the full Cryotone compliment for the UFO25. When I first got the amp I decided to just transfer the tubes from UFO and use the Cryotone VR tubes. Mullard GZ33, SV83's and an Amperex 6DJ8. The sound was good, and sometimes great then sometimes just not right. This is where a long string of mistakes and assumptions occurred. I went forward with the assumption of "if something isn't right then look up the chain for the issue". I knew my turntable was setup good, the tubes in the ZP3 were to my liking, so I went nuts with rolling tubes in the CSP2+. Again went though good, bad and ugly. At this point I put the CSP2+ back where it was. I now dove into the UFO25 tube rolling. I replaced the Cryotone OA3 with a pair of OB3's. Better, much better, but still not happy. Rolled the input VR tube and that wasn't it. In the UFO I REALLY liked the SV83 and stubbornly ignored rolling them, they just can't be the issue I kept telling myself. One night I finally put in the Cryo 5AR4-WC v2, EL84-WC and ECC88-WC. B I N G O ! ! ! It was the SV83's that just didn't work for me in the UFO25. I've kept the Sylvania OB3's and a Raytheon OD3, the Cryotone VR tubes just don't sound great to me, with them in the sound is too edgy, sounds didn't "end" well, ragged and edgy. The sound also leans a ton towards bright which is no good for me. The sound just had a huge bump in the upper mids into the highs, some may like that, to me it was quite fatiguing.

I felt the same as you about the "tiny" 5AR4's, I liked the sound of the larger tubes but for my room, system, ears that tiny 5AR4 works better than Mullard GZ32 or GZ33 which really surprised me.

As far as going full compliment of Cryotone, my personal opinion is the rectifier, output and input sound great, the VR tubes I wouldn't recommend - BUT, they may work for you.

Good luck getting it dialed in, once you get close the experience is jaw dropping!

Congrats on your 25, Bri. I mostly concur with Sean on his thoughts. I have not used the Cryotone VR tubes but found glutton supply of inexpensive 75c1 available online to be perfectly suitable.

There is a magical synergy with the Cryotone 6p15ps and their ECC88. In my room with the music I listen to this combination is the best I have been able to find for energy, detail, and a tightly controlled low end that is extremely present and satisfying but not inflated at any particular low frequency.

Hi HiFi Bri,
Congrats on the UFO25! I saw photos in your other thread and it looks stunning. The grain on the walnut base is beautiful. Looks like you have a great setup going!

I’ve had mine for a little over a year now and it really is an amazing little amp. I found that the bass got fuller and more textured/controlled after about 250-300 hours. So you should be pleasantly surprised. I’ve also tried several EL84s that I had from a prior amp, as well as the Cryotone EL84 and can tell you, the Cryotone sounds clearly better than the other EL84’s in this amp. There are a lot of discussions of the Cryotone EL84 and some comparisons with other EL84’s and the Cryotone 6P15P, that may be worth perusing, before you go for it. I currently have Russian 6P15P-er tubes in, along with other NOS tubes, but am awaiting one more 5U4G-WC, to put back the full compliment of Cryotone tubes to see how that works out. I also use other RCA/Raytheon/Sylvania VR tubes with the Cryotones in the amp, but will be using the Cryotone EL84 and ECC88’s for my amp and preamp, once I receive the other 5U4G. Enjoy your new amp!

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I started my journey with Cryotone EL84-WC after Steve commented on his experience.  I mixed and matched and ended up with a full set in my UFO25.  My choice for the input tube was the Cryotone 12AU7-Long Plate.  For me there's no going back.

In fact when I eventually get the pair of UFO25's that I have on order, they'll have a full set of Cryotone tubes, already have a set waiting.  The only "itch" that I have and will scratch at some point is to try the 5U4G-WC and compare it to the 5AR4-WC-V2.

I've commented at length in past posts on my experience and that has earned me the nick name "Mr Freeze", deservedly so.

I'm divided on my opinion with this. . . imo it depends.

In my large living room/dining room space with my audio/visual system all but one tube (a rectifier in the amp) is Cryotone and with the ZBIT and ZROCK2 there and the CSP3 preamp with all the mods I can get a great sound out of that system. The large room lets the sound develop and there is enough power to do so without strain thanks to the amazing HR-1 speakers.

In my main system a full complement of Cryotone tubes was just. . . too much for me. Too much high end energy and a certain lower treble presence that I just don't enjoy. I sit closer to the speakers here, and the room is long and narrow with the system at one narrow end (by necessity). In this system a non-Cryotone tube in my ZROCK2 and with non-Cryotone tubes in the voltage regulation spots and the rectifier and output tubes is just the right combination--that odd lower treble presence is mitigated by a stronger mid-range, and there is less high frequency energy in general, a good thing for my room and tastes.

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If you're up for it try the Cryotone 12AU7-Long Plate (with an adapter) in the input position of the UFO25.  The VR the for the input in my UFO25 is a Raytheon OC3W

Your set up is very similar to what mine was.  The speakers I'm running are the Omega Vintage 8.

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Couldn't agree more!  Just found out first hand what a difference the room makes, not that I didn't know about this I just didn't experience it to this degree till now.

Bought an old house and started to restore it.  My sound room is 16'x11.5'x7'8".  Actual height was 7' but I took down the drywall and stuffed 6" safe&sound rockwool in the joist spaces with an acoustic tile surface mounted.  It's not finished yet.  At this stage just speaking in this room shows how pleasant it is without the echo that's present in the adjoining room.  Listening is effortless, in fact I can't stand being in the adjoining room, going to have to do something about that.