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.