Latency on amplifiers optical input DAC?

[Roman Empire]

Dear All,

For some fun in the living room, I´ve set up an rpi 4 with a midi keyboard and a toslink cable connecting it to my 10 year old Onkyo amplifiers optical input.
If I use a buffer of just 128 samples (in Ardour and Reaper), I feel the latency clearly when playing through a virtual instrument on the keyboard, although it´s telling me that the latency is just 5.8 ms. I´d say that it feels more like 13-ish ms, so I´m wondering if there could be some extra ms added in the amplifier - anybody with experience in that field?
Would hate to have to buy another hifiberry (got the digi+ one) with analog output for replacement plus rca cable (7,5 m).

[lfm]

All DAC's have latency, not obvious but some daws like Cakewalk specify separately asio buffer and DA and AD converters delay. Some present just total.

If I remember correct DA on my RME HDSP9632 is 141 samples(and AD was 111). And using ASIO buffer 64 samples you just add the stuff to get roundtrip.

DAC's made for music listening purposes usually have rather high latency.

Analog part is nothing you will notice in amp.

Remember that a plugin even having 1 sample delay in Reaper will add a full extra ASIO buffer for monitoring through.

You can calibrate and record amp output back to interface input and record and see what delay really is.

[Roman Empire]

All DAC's have latency, not obvious but some daws like Cakewalk specify separately asio buffer and DA and AD converters delay. Some present just total.

If I remember correct DA on my RME HDSP9632 is 141 samples(and AD was 111). And using ASIO buffer 64 samples you just add the stuff to get roundtrip.

DAC's made for music listening purposes usually have rather high latency.

Analog part is nothing you will notice in amp.

Remember that a plugin even having 1 sample delay in Reaper will add a full extra ASIO buffer for monitoring through.

You can calibrate and record amp output back to interface input and record and see what delay really is.

Yeah that´s why I´m thinking of trying analog instead - just don´t like the extra expense if it turns out to have no big impact.
I got no 7,5 m cable going back to the Pi´s input so I won´t be able to see what the amp´s latency is..

[lunardigs]

The virtual instrument itself induces a latency too, plus any other effects plugins you might use inline with it.

The overall latency is your interface round-trip, plus whatever else you're doing.

When it comes to keyboards and guitars with spiffy effects, I'll just bear it.
When it comes to vocals, I'll usually monitor in the analog domain.

Thing is, once a project gets bigger, and the overall latency goes up, invariably I'll have to monitor performance recordings in the analog domain.

This is why analog gear is still indispensable. Amps and mixers, outboard compressors, etc., it's all still very useful this day and age.

[lfm]

Yeah that´s why I´m thinking of trying analog instead - just don´t like the extra expense if it turns out to have no big impact.
I got no 7,5 m cable going back to the Pi´s input so I won´t be able to see what the amp´s latency is..

I don't know what is available in Pi, but if possible I would set 64 samples in Reaper. That's what I had to do 7 years ago, going from 128 samples which were fine with other daws. And it turned out well, and ran 64 samples since in all daws.