PreAmp or Integrated Amp

Wanting to improve 2 channel listening!! I've been told the weak link, for 2 channel music, in my system is the HT Processor (Integra 9.8). Would I benefit more from a good 2 ch preamp or an integrated amp. Both would have to have HT bypass, as I would like to keep the Integra for the occasional movie. I have a Rotel RMB1077 amp driving B&W 804s speakers. The amp is 100w/channel (7 channels). Budget would be $1500 to a $2500 max.

Thanks for any recommendations.