Tube Pre-Amp for Luxman L525

Hi Forum Members some help please. I have the Luxman L 525 Integrated Amp ( 1980's ). Trying to replace the Pre-Amp section ( it comes apart) with a Tube Pre-Amp to maybe get a more mellow sound for Jazz and Clasical. My budget is $ 1500. max. The speakers will be Kef R-300 Bookshelf. The Amp has been with me from new it is 110 watts per at 8 ohms.As I listen to the music, when with company, the level is more low than laud. That is why the speaker selection changed from Dynaudio 1.3 Mk 2 to Kef R-300. Any suggestions will be very much appreciated. Regards and thanks. Peter
Hi Again, further to my original post I neglected to state that the power amps input, main, impedance is 40k ohms. Also the Luxman is a SS amp. Sorry about that error. Regards Peter
Why not try a cheaper approach by using a Tube Buffer. This may help but probably won't Affect the tone dramatically. I love me AES AE-3 that uses 6SN7s which you can change (roll). For you I would suggest the following tubes NU GT gray glass or the RCA Red base 5692. the 6SN7 are easy to find as old stock asnd even as NOS, either one is warm and rich. You can buy these preamps at Upscale Audio, they are not very expensive by high end tube preamp standards.
Wow!!! I second Mechans terrific advice. That's what I would try first, and I'm fairly certain it would work well.
Thank you Mechans and Mikirob, I do not know anything about tube buffers. Do they go between the Pre-amp and Power amp on all inputs I need 5? Searching thru the internet I read that people use them between CD players inputs and the Power amp. I would need the warmer sound for all inputs in stereo. Regards Peter