have the owners manual pdf in front of me and it claims 5 ICs total.
By reading between the lines it sounds like (just says five integrated circuts)
1-line input buffer op-amp
2-buss input buffer op-amp
3-buss output buffer op-amp
4-? op-amp
5-Lm1877 Headphone amp
the "buss" mentioned has to be a mixing buss , hence the op-amps operate in the inverted mode and that is why there are so many stages.
LINE IN=inverted op-amp
BUSS IN=inverted op-amp
MIXING CIRCUIT =inverted op-amp (output is non inverted,adding two negatives = one plus)
BUSS OUT=non inverted op-amp
HEADPHONE OUT= non inverted amp IC
The cool thing about this product is
A-socketed op-amps in a commercial device is VERY rare.For those that enjoy tweeking the sound it is WAY COOL !
Pop one out,one in ,listen,decide,put the cover back on
COOL !
B-the "buss" output means you CAN have your cake and eat it !
You want a comparison between the op-amp?amp combo against the straight op-amp ?
Put a headphone adapter on the buss output !!!!!!!!!!
Simple,classic