RE: critical speaker frequency:
According to this [1] 480Hz is either the critical frequency or well on the safe side. (I'm no audio expert)
So muting everything below that frequency in alsamixer should make audio safe.
Who want's to play the guinea pig?

On another note, I finally got around to install Debian on real hardware, installed LXDE and it works mostly fine.

I found some small issues:

1. After a reboot when I select Maemo (CSSU thumb kernel sitting on eMMC) the first attempt to boot will always fail at the 5 dots of dread, the second one will always be fine. No idea if it's a Debian, a u-boot or a CSSU thumb thing.
2. In LXDE tapping the screen will always trigger the right mouse button which makes it hard to control the desktop. I guess that's manageable via evdev. Reading man evdev also revealed that tap-hold for right click can be configured via evdev and therefore desktop-independent.
3. I noticed that the CLI and GUI keymaps differ (e.g. no Tab via Shift+Space in GUI). Where is the CLI keymap defined for comparison?
4. LXDE battery monitor may not work. I say "may" because I only tried with power cable connected.

Other than that I'm quite impressed.
btw. is there an easy way to overclock the CPU within Debian, probably the same way KP does it in Maemo?
I didn't try phone functions so far, but I'll try soon. Unfortunately the fso-deviced package isn't installable on i386/amd64 atm. Not sure if it's any better on armhf. I guess it's due to changes in connection with systemd introduction (but right now it doesn't work with sysvinit either).


[1] http://213.128.137.28/showthread.php?p=1160889