warmer and better bass sounding tube,please

Hi, I am looking for a tube upgrade to replace the stock tube JAN6922 that comes with the AhTjoeb4000 CDP.I am expecting for a more bass and warmer sounding tube. My other system are:NADC370 amp;Analysis plus Oval 9 spkr cable;TruthLink IC.(harmonic tech),Quadral Ascent 850 spkr(
3 way,bass reflex,floor-standing,89dB,4-8ohm). Your opinion and suggestion is highly appreciated and thanks a lot.
Simon