I'm considering replacing my passive preamp with a tubes. Is it worth it?

The answer is "maybe". Some will tell you "yes", some will tell you "no".
Since it's your money, the only opinion that really matters is your own.

So you should just look for a tube preamp on the used market that is a good deal and try it yourself. If it works, great. It it doesn't work out, sell it, and go back to the passive. At least then you will know for yourself.

I totally agree with jmcgrogan2 it depends but I see some pretty cool tubed preamps for sale here in your price range.

https://www.audiogon.com/listings/tube-blue-circle-audio-bc21-1-tube-preamplifier-upgraded-9911-2017...

https://www.audiogon.com/listings/tube-lector-zoe-tube-preamp-2017-02-12-preamplifiers-40059-prospec...

No affiliation with any sellers those both look like good deals and good preamps, good luck and happy listening!

What would I expect to be different with the tube preamp?

The opinions are appreciated so thanks

amritash I’m considering replacing my passive preamp with a tubes. Is it worth it?

Schiit Freya at $699 with trial period, it has 3 different modes, low gain tube, low gain discrete solid state, and unity gain passive, balanced or single ended and with remote control.
And with the Bryston 4b-s input sensitivity being only 1.4v input for full output, you don’t want any higher gain or the volume control will be down very low for loud listening, and you’ll have very little range on the volume control..

Can’t go wrong with this choice best of all worlds, specially seeing it’s designed by Mike Moffat who was head designer at Theta.
http://schiit.com/products/freya

Cheers George

The two preamps listed on Audiogon are highly rated for sonics and build quality.
But the Schiit is getting raves for its price and performance. Plus, you could run it balanced to your Bryston.