Tube-Curious/Pre-amp

Hi guys

I've been toying with the idea of tubes for a while, and was wondering if a tube pre-amp would be worthwhile pairing with my Class A/B integrated - Atoll IN200 Signature (the Atoll has the function to bypass its own internal pre-amp section, and pair the power section with an external pre-amp).

I predominantly listen to Jazz (all eras, all flavours) and am very interested to hear what tubes would bring me; I've casually read around, and the description of sound from reviewers and regular users does appeal to me greatly. 

I am aware of the Schiit Freya +, and from what I can make out, with some tube swapping, the Freya can produce some good results; but apart from this I'm not really sure what I should be looking at. I'm not looking to spend multiple thousands on this little side interest, or replace my Atoll./Solid State, but to just give myself an exposure to tubes in my audio chain. 

The other option I suppose, is to look at the offerings from Willsenton as an additional integrated, such as the R300 (this seems to be well received, and at a  reasonable price tag). 

Any advice/guidance gratefully received

Thanks very much 👍