Krell KAV250A upgrade to FPB300?

Hi all

My system is as follows:

Krell 300CD
Krell KRC-HR pre
Krell KAV 250A power
Aerial Acoustics 10T speakers
Cardas Golden Cross XLR interconnects
Audioquest Clear 3 Speaker cables
Essence ESP power cords

I am looking for more truth of timbre & realism in my system, which although very musical, stills sounds a little hifi-ish. My former speakers, ageing Martin Logan Quests, were rather better in that respect, although the Aerial 10t's are superior in all other areas, esp the highs and of course the bass. (Extremely high humidity here made the Quests' high frequencies severely rolled off). I understand that there are things that a 'stat does in the midrange that other types of speaker never seem to achieve, but I would love to get back some of the mid range magic that can make a great system so goddarn seductive.

I replaced my Krell KAV 250P preamp with the KRC-HR, as I plan to upgrade my power amp to a Krell FPB 300, or if I can afford it, the FPB 600. The preamp upgrade brought an incredible improvement in resolution, but the lack of beauty in the mids still remains.

I'm trying to identify which area needs to be addressed to achieve this.

Do you think the FPB 300 will bring about a big improvement, or should I hold out longer till I can save the extra green required for the FPB 600?

I'm also considering adding a Chord DAC64.

All advice and opinions welcome,

Thanks in advance for your help,
Mickey