To my understanding:
A 2volt HU will produce a 1volt signal when the music is at 0dBfs (loudest). Each 6dB you boost a signal it will output an additional amount voltage. So a 2volt HU can boost audio signals a maximum of 0dBfs + 6dB (1+1 = 2volts) before clipping.
the 4volt HU's are capable of a maximum of 0dBfs + 12dB (1+3 = 4volts).
My question is, a pioneer premeer 940MP claims to have 6volt outputs. Their dsp specs however only claim to be able to do +- 12dB. (4volts). Are there any ways these 2 remaining volts would ever be utilized or is it just hype from pioneer?
Here are 2 links with relevant info:
Description of voltages