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

I've actually gone from a tube pre to a passive. I used to own an Octave Audio Phonomodule. At the time, i thought it sounded good. That was until my mate brought his Dave Slagle autoformer TVC over. The difference was day and night. Soon after i built my own and have never looked back. I will never go active again. 
But as they say, it's all system dependant. 

A used  Rogue Metis preamp should be in your price range. For the price a nice tube pre with easy tube rolling. Have been using one for a year now and I'm very pleased with it.

amritash,
Congratulations on your new acquisition. Enjoy it.

Out of curiosity - what was your passive preamp?
Alternatively you could have purchased a Bluetooth DAC which has a healthy 2V out and kept your passive, if you like it's sound. You still should get a Bluetooth DAC, rather than connecting the iphone directly to the preamp.

Hey

So Ive received an have listened to the Audible Illusions modulus 2d.I am in love. I put inReflector 6H23p-EB / 6922There is absolutely no comparison between the Mod Squad Line Drive passive. The AI sound is just so beautiful. I think that I’ve finally heard the audiophile sound. I could listen to this and do for hours on end.
Now that I have been bitten I’m curious what I can do with an upgrade on it. The small thing that I would like hear is an improvement is the highs being a little more distinct. Imaging on the AI is great but I know there is better. Im considering some but I’ll post the question in a separate thread.

thanks
Adam

http://www.thetubestore.com/Tubes/6922-E88CC-Tube-Types/Telefunken-E88CC-6922