El34 vs. KT88

I'm not clear if you're asking the question so that you can narrow your choice of amps but it isn't necessary to make the decision between EL34 and KT88 power tubes in advance. Quite a few excellent integrateds will let you use both those tubes, and many others. The Primaluna Dialogue is one, as is the Cary Sli-80.

If you're fairly new to tubes that's a really nice feature. Being able to change tube types lets you more easily match the sound to your other equipment and discover the sound you prefer. And tube rolling is fun.

The first tube amp I bought came with KT88, EL34 and KT66 tubes. Ultimately I listened primarily to 5881s and KT77s but someone else, with a different source, speakers and taste in music, would likely have had a different preference.

I am a big fan of the EL-34 tube, I find it combines a lot of the warmth of SET tubes with more power levels and in the right implementation can sound fantastic. I have a pp 17 watt EL-34 amp and I could not be happier. This was after running through 300B's, and 6550's in various amps. I have not checked out KT-77's but may have to soon. Another bonus of EL-34's is they can be super cheap to replace, one of the reasons I opted out of 300B's was high tube replacement costs.

I have SED EL34's - 6550's and KT88's. The EL34's have that great mid range magic that is hard to beat but lacks lows - highs and power. The KT88 has a world more bass and a little more in the highs. The 6550 on the other hand is extremely linear from top to bottom. Again those are all SED's. My Tung Sol 6550 solid black and grey plates have that EL34 mid range with the lows and power but still a little rolled off in the highs. Now unlike the SED KT88 the EAT - Gec and Tesla KT88 have the best highs with a good mid range and great lows. Except for the EAT the Gec and Tesla are expensive vintage tubes. EAT is currently being produced and expensive. The EAT were/are my favorites. I mean they are my favorite in sound but not reliability.

All that being said you need to get the amp first and try different tubes. I found with my Octave V70SE integrated the input tube can alter the sound the most.

Consider the quicksilver silver 88 or silver mono...simply magic with Vandys. The m60 quicksilvdr gives you el34 or kt88 options.

I am running Quicksilver mid monos with kt88s, the added power of the kt88s were a big step up from the stock el34s. Mostly in dynamics.