As in the Grand Integra M-510, Signal In-Phase Filters and Charging Noise Filters iron out differences in current and load between the P-308 and the amplifier.
The Integra M-508 is a miniature M-510 : same technology, same Real-Phase circuit. However, the box dwindles from 62kg to a mere 25 (still quite healthy !) and the overall build-quality goes with the price - not with the 950,000¥ of the M-510.
Dual-transformers, too, but only one power cord and the eight caps amount to 80,000µF. The two Real Phase transformers are outlined in white on the image below.
Mostly, inside, is the Linear Switching circuit, also used in the M-510 : high-bias and wide-bandwidth (20MHz) power transistors to prevent crossover distortion and increase the Class A operating range without a sliding bias system.
Simulated wood sideburns for all and, bar the lamp dimmer, the M-508's functions are identical to those of the M-510.
Also gold-plated terminals and a Grand Integra badge. Said badge in the original japanese versions was however placed elsewhere and only said... Integra :)
The M-508 at Onkyo.