Burr Brown OPA 2143 vs NJM2068

TL... is probably TL082 or 72 or 62 or something from this family (pretty bad for audio). If you can go with OPA2134 (dual) then go with LM4562 - it is exceptional amp. It is probably 8 pin DIP thru hole plastic package (2 rows 0.3" apart of 4 pins each 0.1" apart. Pinout of packages is standard - always the same. Both OPA2134 and LM4562 are dual and pinout is the same. Be sure that package is plastic DIP as I described a not a metal can. Metal can package (not very common) can be soldered into DIP (same order of pins) but not the other way around. LM4562 is available in all versions. When you change amps go for the best and most expensive. Few dolars more won't make any difference to you. It makes often difference to manufacturer but sometimes reason is different. They just simply cannot constantly change amps when new and better once are released (every year). It would require prototype testing over and over again and create nightmare in service. I suspect that they never change to better amps without a big reason. Design is treated as closed. Be sure to test your amp with cheap speakers. In spite of op-amps being stable there is always a chance as with any repair of bad solder joint or short - very small chance but still..

Kijanki, I recall he said they were 4 TL081. I´m sure he said they were 4 and not absolutely sure the model. I think the TL081 are the single versions og the TL082. Another technician advised me to use AD818. Do you know them? I have them in a DAC. Thanks for all the other advise. I´ll use it when I take it to the technician I choose.

Joaco - TL081 is a single amp. It is very old and very cheap amp designed as a improvement over 741 type (one of the first op-amps). It is not an audio amp. LM4562 comes in single version with completely different number starting with LME.... - I have to check again.

Generally, not a good sub. OPA2134 is FET-input (higher noise voltage, lower noise current) and NJM2068 is bipolar (higher noise current, lower noise voltage). This means that they're optimized for different circuit impedances.

What's wrong with using the original part?

What's wrong with using the original part? - without going into technical stuff let just say that Texas Instr. introduced this part in October 1976 and LM4562 was introduced around 2006. Not only 30 years difference but also TL081 was design as universal amp while LM4562 was designed specifically as an audio amp (with incredible DC spects).