Pioneer AX10Ai AV Amplifier DAC Queries

[markabuckley]

query regarding the criticality of op-amp selection at different points within the audio chain please.

I've been reading these forums for a while.

AX10Ai (59TXi in US) - has the following from looking at the schematics from Pioneer (which are very informative) and looking at other sites

for each channel

PCM1704 (quite high end in all accounts)
5534 op-amp for I/V converter purposes (next to the DAC)
JRC2068 op-amp post PCM1704 (as a filter)

then a single OPA2134 at the pre-out stage

it confuses me - why in a high end amp they'd go to the expense of an expensive DAC, a decent op-amp at final (pre-out) stage - but then use JRC2068s post the DAC.

what I'm interested in - does quality of the op-amps depend on their particular purpose required of them in the circuit.

and what would lead them to use such an odd mix - or is it just to do with cost ?

thanks for an info,

Mark.