Plinius 9200 or separates?

Trying to get a grasp of how to proceed with amplification. I have a Plinius 9200 running Totem Forest speakers. Sounds good but not incredible. Recently subbed in some 70's era Audio Research pieces (SP-6 pre amp and D52-B power amp). These have in the past had some problems with distortion but worked this time just fine. It seems like the sound came more alive with this combo although it felt like some more power was needed, especially with orchestral music. I was told by a repairman that the power amp was on its last legs. I'm considering having AR service the SP-6 and look for a new power amp.I would appreciate opinions about what power amp, tube or SS, might be appropriate. Or should I look for another pre amp as well? I know this is kind of vague but what do you think?

Plinius 9200 w/ Top Gun power cord
Totem Forest w/ Totem bi-wire cable
Rega P3
Exposure 2010S CD