This amp is just so good with the Utopia.. Have been listening with it for a few days in a row.
I thought the EML 2a3 tubes were good in the Stellaris, but swapped in the KR 2a3 tubes and they're even better. Super clear, airy and detailed. Very nice mids, although not as thick or lush as the wa33. Very very tight punchy bass. A very dynamic and engaging overall sound!
If I was going to start all over again, and wanted to have a rig centered around the Utopia, this amp would be a top choice.
The downside is.. For my other headphones like the Stellia and VO, I find these sound better with the WA33. The TC and Susvara can be driven with the Stellaris, but the treble energy is a bit much and the highs seem a bit strained. Also, the soundstage I'm getting is noticeably smaller than with a speaker amp.
The amp itself weighs a fair bit. One of the 2a3 sockets is looser than the other. The blue paint job looks nice but it is a scratch magnet..! I guess it would probably benefit from a nice strong clear coat during the build. Otherwise, never use a tissue, or anything less than a super soft microfiber cloth to clean it..
Audible clicks and pops when turning on/off the amp is a slight annoyance. Also, more usable volume would be nice with the Utopia (max is 1.5 on the knob for me..). This is the single ended version.. Not sure how the one with balanced connections will fare.
Wish I could try my tak274b on it.. But unfortunately it is limited to 5u4g recs.
So again, if centering solely around the Utopia, this amp should be high on your list. But if u have other headphones.. Then I'm thinking the wa33 will be a better choice.