New speakers but old Rotel Amp


I got the Harbeths 30.2 XDs about a month ago and love them.
I have a PL Evo 300 preamp (an Evo 400 without balanced connectors), have a VPI Prime Signature TT with a Hana ML low output MC cartridge, a Musical Surroundings Phonomena (1st edition) phono stage that will be replaced next year, and my 19 year-old Rotel RB-981 amp.
I'm wondering if I should just get a PL Evo 400 amp, but the dealer I bought the speaker from said I could have done better, and is suggesting a BAT-56 (non SE) or a Rogue, or a Bryston 3B3 amp.
My budget was $5k, but listening to Riders on the Storm my wife heard so many new layers of the music she actually said the speakers were definitely worth the money and was interested in it sounding even better. I didn't tell her the stands were extra. The closest audio dealer is 45 min away and he suggested SimAudio. I was thinking tube amp not solid state.
128x128ctwith3
A sugden class A integrated would pair nicely with the Harbeths. SS, but sound like tubes. 
my wife heard so many new layers of the music she actually said the speakers were definitely worth the money and was interested in it sounding even better.
Hot damn!  You married well.  Would be most helpful in making a specific recommendation if you could share what you’d like to improve upon further and what aspects of sound/system performance you value most. 
Need better bass- controlled with slam, larger soundstage, and I have heard anything else in a long time to compare it to for a better response to your question.