However, this is not an explanation if the low frequency range has changed even at low volumes.
Generally speaking, the impact on Damping Factor will alter the low resonant frequency of the drive system (I've had the opportunity to measure stuff like that with a work colleague with test equipment way back when). It may impact the phase of the audio through the system as well (this I've never measured, things like group delay).
Damping Factor is all well and dandy, and the minute I hook up my speaker cables, the damping factor should take a hit (I'm using the Benchmark cables with NL2 connectors).
So here's a perspective:
1) hook up your speaker cables and measure the Damping Factor with cables attached in stereo mode.
2) Bridge the amp and repeat the measurement.
I am more than expecting that the change will be so small that the impact on the sound would be minimal; at least to my ears.
How this impacts the sonic signature and is perceptively heard is beyond me. The extra power and impact to the system has changed, I note the changes through my filter and report them.
As I stated, there seems to be more bass, but it is very subtle; it could even be that the bass frequency is the same but the woofer is just receiving more energy.
If bass was the only reason to 'bridge', I'd save my $$ and keep the amplifier in stereo mode and call it day.
Alternatively, the results I note going to "bridged mode" or 'mono mode' surprised the heck out of me: I was expecting more power, more slam, more volume in a high level kinda way; I noted more air, more presence and more fluidity and a wider soundstage (depending on material used). It's a more sophisticated sound all around.
Makes me wonder how a small rated amp like Schitt Aegir would respond in 'Bridged mode'; which has many fans on other forums as well. In Canada, quantity x2 Schitt Aegir is starting to get up there in price due to exchange rates and makes me wonder: should I take a punt and try it for my second system?