Are passive preamps better?

It will be quieter and maybe more transparent, which does not mean it will sound better to you. You are going to hear 50% argue for passives and 50% swear by active tubes. Ultimately you will have to try four yourself, but there are certainly very, very good passives and happy owners. I know this does not help much, but it is hard to to give a definitive answer that is warranted. I've been the passive route, and prefer my tubed Joule 150 MKII.

Agree with Pubul57,

My response to passive preamps is no.

With passive you have the hardware in the way, volume controls in the way, wire in the way, RCA (or XLR) jacks in the way but you get ZERO benefit.

Zero gain, zero contrast and zero dynamic enhancement from the original signal.

I agree with Albert and Pubul:

Right now I'm listening through Endler resistor-based volume controls ahead of Atma-Sphere MA-1s. Nice combo, but I've got a custom Audio Note kits L3 active in the UPS pipeline that'll replace the Endlers with no regrets. I've also used the DIY HiFi Django w/S&B iron ahead of Atmas as well - again nice, but ultimately lacking the energy imparted by a Blue Circle BC-3000 or Atma MP-3 (the last two actives in my system).

If one has $1000 or less budgeted to a "preamp", I'd go with a passive; otherwise, I'd save for a quality active preamp.

I had an NVA passive pre which....delivered music "as is". When I tried an Audio Note tube pre, the music became alive. So I am now an active pre camper!