Well, I had a brief session with my friend's IPad with the 'SPL Meter' App installed. What a cool device - I may have to get one!
Assuming that it is reasonably accurate, my sound level comfort level (when I'm sober, ha1) is about 75 Dbs Average with the absolute max being 85 Dbs Average.
Spiro Gyra 'Good to Go-Go' SACD is recorded very hot. At my seating area of 8 to 9 feet, my tube-amp levels (o'clock) gave me roughly:
* 10 o'clock - 75 Db Ave / 79 Db max;
* 11 o'clock - 85 Db Ave / 88 Db max.
At the back of the room 25' away from the speakers:
* 10 o'clock - 70 Db Ave / 75 Db Max;
* 10 o'clock - 80 Db Ave / 82 Db Max.
The Cameron Carpenter SACD is recorded at a much lower average level that gave me 65 Dbs Ave / 70 Db Max in the listening area.
According to the specs that I've read on the output of the EP-400, I must conclude that it could capably do the job for my audio only system in my setting by providing more than adequate, clean & accurate bass response.
Thanks to all for your interest & assistance. Comments are most welcome...