High end high quality int. amp for low level listening


Hello to all Audigon members.  I'm quite in a dilemma weather I should upgrade my amplifier. Currently I own Pathos classic one MK3 driving Sonus Faber Sonetto's speakers, and I must say I'm very happy with sound filling my 35 square meters room. However, it's known that the speakers are power hungry as they rated at 86db sensitivity and 4 ohm impedance and I think they will surely benefit from a bigger power supply. With all that being said I'm not sure if I will hear any improvement mostly because 90% of the time I listen at ~60dBs SPL. My budget is around 5k $ and these are the amplifiers I've been considering:  Hegel H390, Anthem STR, Cambridge Audio Edge A, McIntosh MA5300/MA252, Accuphase e280, Rotel Michi x3 or used Pass Labs INT 25, Mark Levinson 5805.

What do you think guys, will any of the amplifiers make ay difference at 60dB SPL ? 
celestial__sound
There aren’t too many integrated amps that double their power wattage into 4 ohms. The Levinson 5805 does (125 watts into 8 ohms, 250 into 4 ohms).  If you decide to keep your speakers, I would lean towards it or one of the Hegel integrateds myself. 
having subs in the mix will lessen the load on the amp and allow lesser sensitivity
How big of a concern is the load on the amp, when the SPL is in the 60s of decibels?

@holmzI think ditusa above answered this better than I can. I’m not an electrical engineer, but it has to do I think with the quality of the first watt. Yes 60 decibels is the same volume in two different setups, but the amount of distortion and  resolution heard at that level can be vastly different.  I think you want dynamic headroom listening even at 60 dB. 
IMHO, keep the Pathos and get high efficiency speakers or one with a benign impedance curve (e.g., Fritz Carrera Be, ProAc Response D2, used Joseph Audio Pulsar). I think high efficiency speakers sound better at low volumes than low to medium efficiency speakers, but just my opinion — based on tube Coincident Dynamo 8 wpc amp driving Klipsch Heresy IIIs (99 dB/1 m) versus 125 wpc solid state Belles Aria Signature integrated driving Vandersteen VRL CT (86 dB/1 m).