OPAMP upgrade for Quad 405

uA301ATC is a very old bipolar design, older than a jfet input TL071 as it is a few generations newer but still very old in the opamp world.
What is wrong with using a NE5534A?
BTW I do not know this Quad 405 design so I am speaking in general terms. It does depend on what the part is used for, if it is in the signal path.
I looked at the schematic they have on hifiengine, I think a NE5534 would be something to try. Or even the TL071 as they use in the other version. These are cheap parts to play with.
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The uA301 was used in the very first type of QUAD 405, so I guess you have an original QUAD 405 rather than a QUAD 405-2. The Acoustical Manufacturing Co. made many small improvements in the QUAD 405-2, the most important ones are halving the dead zone of the class-C stage and upgrading the op-amp from uA301 to TL071.
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