Some amps with speaker/line level and some amps with only line level ?

[gstokes]

Why do some amps have both line/speaker level inputs while other amps have only live level or speaker level ?

Is it a matter of input stage for the amp finding it easier to amplify a speaker level signal (24-36V) or use a low level preamp signal (2-6V) ?

Or perhaps a matter of frequency (sub amp vs full-range) or maybe class A or B or AB or D or combo of different classes that dictates what inputs to use, i always thought that a strong preamp signal like 4V going to line level input was cleaner than speaker level inputs but nothing is making sense to me so point me in the right direction so i can do my research and learn why there is difference, thank you..

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[garychoffmann 10+ year member]

Speaker level on amp is a selling point for integration into factory units. I can't think of a amp I have owned that had speaker level input. I imagine it's on a lot of entry level stuff. Just my thoughts. Rca is always better imo

 

[gstokes]

Makes perfect sense now, my MB Quart OA1100.5 is considered entry level SQ component and has RCA but no speaker level..

 

[trumpet 5,000+ posts]

RCA as an audio signal path is an outdated technology that has clung on to the car audio aftermarket because it's an easy profit generator. It's vulnerable to RF interference, which is simple to avoid by using something that does not reference ground. What is an alternative to RCA that does not reference ground? Speaker level/high level inputs!

 

[gstokes]

An optical TOSLINK would work but would also increase manufacturing costs and drive up the price so RCA is probably here to stay for a while..