Denon X4800H bi-amped power on pop

Lots of possibilities, don't have any denons, don't know for sure, but....

If it is "only happening with internal biamp", goes away completely when you remove biamp, it is a DC offset issue (woofer amp channel <-> tweeter channel) exasperated through the speaker’s passive crossover.

If you change the biamp channels, ie...swap the woofer and tweeter channel, the pop might sound a bit different, confirming the above.

Not good for the tweeter.

Stop the biamp.

( denon feature oversight...or something failed, hard to tell, not a issue with the speaker, maybe try updating the firmware or complain to Denon, they may release firmware with a fix.)

@travelinjack wrote

@deep_333 All secondary zones are power off.

I am bi-amping using the AVR since it has 9 separate amp modules.  The idea is to spread the load across separate amp modules and across heat sink.  I get the idea that since they share the same power supply that it may be pointless.

Do you hear any benefit with bi-amping?  If not just go back, but if there is a benefit you could just leave the Denon on as it doesn’t burn all that much power on idle and may actually be better than turning it on/off every day if that’s what you’re doing.  Frankly, your speakers deserve better than a mid-fi AVR and rather than worrying about bi-amping you’d be much better served by getting a good stereo integrated amp with a HT bypass and running the front L/R pre outs from the Denon into that — you’ll get much more out of those speakers.  Just my $0.02 FWIW. 

@soix @deep_333 

On the X4800H, since the main front left/right speaker output and pre-outs are all active, does this mean it's possible to bi-amp using these? 

If I connect the main front left/right to the high frequency on the speakers and then the pre-outs to a pair of Fosi V3 mono blocks which would feed the low frequency on the speakers?

Yes, you can bypass its internal configuration assignment in this manner.

For hifi purposes, you should eventually move away from the AVR and get a purpose designed preamp processor, i.e., it will have no internal amp sections. You connect the pre-outputs of such a processor into external amps or a beefy multichannel power amp. 

Even a flagship AVR is only good for hometheater, movies. For music, you will need a dedicated processor and separate amps and correctly gainstage everything. It is never a good idea to shove all those power amp sections into the same chassis.

For example, this marantz would be a good fit.

https://www.accessories4less.com/make-a-store/item/marav30blk-a/marantz-new-av-30-11.4-channel-balanced-av-preamplifier-powered-by-heos/1.html

Or here’s a refurbished unit for a bit cheaper.

https://www.accessories4less.com/make-a-store/item/marav30blk-rb/marantz-av-30-11.4-channel-balanced-av-preamplifier-powered-by-heos/1.html

This older Rotel, for example would be a good barebones processor as well, with a focus on sound quality for around a 1000 bucks.

https://www.ebay.com/itm/336398263929

@travelinjack wrote

On the X4800H, since the main front left/right speaker output and pre-outs are all active, does this mean it’s possible to bi-amp using these? 

If I connect the main front left/right to the high frequency on the speakers and then the pre-outs to a pair of Fosi V3 mono blocks which would feed the low frequency on the speakers?

I believe the problem is that the preamp in the Denon is not fully powered when the amplifier speaker relay turns on allowing a transient to the speakers. The same is happening on power down. The power amplifier needs to be the last on and first off in the power sequence. Not an easy problem to solve with an all in one unit. Maybe you can use a separate output relay for the drivers?