Funny thing about noise floors, when I had my Brax X2400 back in 2003-2004 I ran an Alpine F#1 Status PXA-H900 processor with it along with Scan Speak Revelator 12M mids and the older version of the current D3004/6020 tweeter. On the IASCA test disk the fade to 0 bits track the music would switch to 0 bits at 1:17 and have a level of -70 dB. In my system I could hear the noise gate in the recording studio click shut at 1:17. After 1:17 it was dead silence. I did not have a noise gate in the system, although some IASCA judges said I did. I even had some judges dock me points because they thought the "click" at 1:17 was some kind of problem in my system. I simply had my system's gain structure set up to have a S/N ratio greater than 70 dB, which was the test track's limit.
Currently I have my Z-LXs sitting in my closet awaiting for me to buy a new vehicle for me to install them in. But when they were in my car last year, in my tuning with my Helix DSP-Pro MKII and the Z-LXs, I could also hear the noise gate click at 1:17 on the same test track.
Plus most people with perfect hearing can only hear a dynamic range of about 75-80 dB. So I figure that any amp with a S/N ratio above 85-90 dB should not have an audible noise floor problem given the
entire system's gain structure is set correctly and all other equipment in the system has as good or better specifications. Of course, the better the specifications are, generally the better the equipment is.
I like to use the Autosound 2000 Test CD #104 and a good (but cheap) oscilloscope to set gains. The CD can be bought here:
Navone Engineering Inc. » CD-104 AUTOSOUND 2000 Test Software
A decent oscilloscope can be found here:
https://smile.amazon.com/dp/B01MSJCUA7/_encoding=UTF8?coliid=IGU5BKFYTDKD8&colid=2L8G4AKPI31HS&psc=1
