How would you introduce tubes into this SS system?


I have a Rotel RC-1070 preamp and a Parasound HCA-1000 amp driving a pair of NHT Super Two’s. The Super Two’s sensitivity is 87 db (2.83V at 1M), 8 Ohms nominal impedance (3.8 Ohms minimum), and recommended amp power of 25W/ch min. and 175W/ch. max. The Rotel’s output level and impedance are 1V and 100 Ohms, and the Parasound’s input impedance is 33 kiloOhms. The budget is around $2000 for either a tube preamp, tube amp, or integrated tube/hybrid amp. I like the sonic qualities of tube equipment, but I don’t want to sacrifice too much bass. I should also mention that I use this system primarily for listening to vinyl on a Music Hall mmf-5.1 turntable. Should I replace the Rotel, the Parasound, or both? Thanks for your opinions.
jackalope
Jackalope, Steve wrote to me and I responded. I've agreed to send him these amps for repair if he can take the project on. I'll let you know what happens.
Well, I've done the thing and gotten the stuff. Ended up with the AR LS16mkll, a McCormack DNA-1 Deluxe Edition, and the Joseph Audio RM22si's. Haven't listened for more than a few records as of now, but the combo sounds fantastic. Thanks everyone!
For the record Steve at VAS repaired one of the two amps that I mentioned earlier at a reasonable price and effectively. Turn around time was good. No problems. Apparently I was wrong about his no longer being a distributor for Cayin. 
The MCormacks are great amps.  You'll love it, and Steve McCormack still services/upgrades them.