I totally understand where you are coming from, selling can be a hassle. But the truth is low level listening has much more to do with the speaker, its impedance curve and its sensitivity, then the amplifier’s characteristics. You already have a very beefy amp which is more then capable of driving your speakers, so if that amp doesn’t do it for you at low volumes, a $1,500 integrated will likely be a downgrade. Plus as I mentioned, high sensitivity speakers may cost a bit more up front, but you can easily get away with a lower cost integrated.
True high sensitivity designs tend to be large to compensate for the bass tradeoff, the Heresy is among the smallest that I know of with a true high 90’s sensitivity. Honestly from a floor space perspective it doesn’t take up much more room then a stand mounted speaker. Are you placing these on a cabinet or shelf? If not I’d seriously consider them, they are awesome. Many people actually place them on stands. I’ve even been to a bar that had some old versions wall mounted. The sound was incredible. I have the Forte IV’s myself and they’ll never leave.
Another way to achieve high sensitivity without a huge box is to get rid of the crossover and use a full range driver. Zu Audio has a few designs like this and they do make a bookshelf, though its a rather large bookshelf. Check out the Zu DWX. I have no personal experience with the DWX though. Others may be able to chime in.