what's the cheapest one I can get that isn't complete garbage?
$50 is about what I would like to pay, maybe $60...
good luck trying to find one for that price. and an O-Scope is the only true way to tune your system to know whether you are clipping or not. 12/14 on your phone volume doesn't matter, your head unit will clip after a certain volume level on it, even if your phone is only 12/14.. Just because you don't hear distortion, doesn't mean you're not clipping.
thank you for saying this. i was going to say the same thing. volume or gain 'position' has nothing to do with output. just because a gain is turned 'half up' does not mean it's 'half as loud' or could be twice as loud if turned more or whatever. preout voltage determines gain position. higher pre out voltage from the head unit equals less gain, and less pre out voltage equals more gain. results are the same however regardless of position. if your phone is on 12 out of 14 on volume, and when it's any higher you can actually hear distortion, then chances are you're distorting at your 12/14 volume, you just can't hear it. only way to tell is with an o-scope. and 200 dollars is cheap for an o-scope, so good luck on getting one for 60 bucks that actually does decent readings. the base o-scope is good enough for audio (the $200 kind). they can get as pricey as several thousands of dollars.