I'm wondering if they are beneficial and if anyone uses them.

I use SLA on Sirius only but it isnt really a necessary feature and I could do without it

Loudness is a defacto standard for all radios it seems, and yet its completely useless. If you have to use that button, you need bigger amps, better speakers, better hearingaids

I use SLA

I used to not use SLA and keep loudness on Low but now I turned it off and jack up SLA all the way.

SLA should only be used to level out different inputs. If you are listening to your IPOD and go into SLA you will notice you can set it different fom XM, etc. The only option not avaliable is FM. The point is so you do have large volume changes when switching sources. If you are cranking it up to get more power you are also adding distortion to your system. Loud is just the interan power on the head unit. Can be used it is not the cleanest power but on low or med it can make up for some small amp issues and not trash your sound quality.

SLA should only be used to level out different inputs. If you are listening to your IPOD and go into SLA you will notice you can set it different fom XM, etc. The only option not avaliable is FM. The point is so you do have large volume changes when switching sources. If you are cranking it up to get more power you are also adding distortion to your system. Loud is just the interan power on the head unit. Can be used it is not the cleanest power but on low or med it can make up for some small amp issues and not trash your sound quality.

P.S. The reason FM isn't available is because SLA adjusts all OTHER sources relative to FM...FM is taken as the "standard" level by the AVIC. So you can make XM stronger or weaker relative to THAT, for example.

yes i have the SLA set to make all the different sources play at the same level (or as close to it as possible)

nut i do not use the loudness settings at all, it seems that the loudness boost the lows and highs but only at lower volumes, at higher volumes, the bass and treble seems to fade out a little bit. turning this feature off seems to remedy this and give me much more consistent sound at all levels

I turn it all the way DOWN so that I have less chance of hurting my speakers.

And I already turned the gain on the amp to half and the bass boost off all the way...

This head unit it LOUD