There seems to be much adieu about sound pressure.  Everyone wants to know "how loud will it go?".  Most commercial folks will measure the SPL at 1 meter.  The problem is that the measurement often doesn't indicate if these are the peaks, the average, or something worthwhile.   They also don't indicate what frequency the sound pressure was measured with.  My simple method is to apply a measurement reference that most folks will understand.  I use my Snapper 6hp Briggs & Stratton lawn mower engine for a reference.  Most folks know what one of these sounds like. The Briggs & Stratton 6hp engine on my Snapper lawnmower produces about 85db average at ear level using my Radio Shack sound pressure meter. The 1801 will produce about 90db average in my listening chair with a pop-music track by Steven Curtis Chapman.  After 90db there is some audible compression.  The 1801 won't blow your eardrums in quick fashion, but is easily capable of sustained ear damaging volume.  It gets the job done with class in my 8'x14'x17' room.  Thus, if you have any questions concerning the amount of sound pressure needed for your listening room there is easy resolution.  Pull the lawn mower into the living room (when your wife is not home), and start that engine!  Is it loud enough?  If so, the 1801 will be fine too. My amplifier is a Bryston 3B-ST (120wpc) and I have the volume knob at abut 2/3rds gain when achieving the 90db SPL in my listening room.