PianoTeq is relatively efficient so does not require expensive computing power. In my experience, you just need good ASIO drivers and a decent computer to run PianoTeq at very low latencies.
How shall we define latency? For digital pianos, a practical approach is a simplified "round trip", or the time it takes between pressing a key and sound arriving at the eardrum.
How much latency matters for digital piano? There are a lot of general latency studies and results might differ by person, activity, skill level, etc. Maybe a beginning pianist is less sensitive whilst a professional drummer might be more sensitive to latency.
Maybe less than 10ms "round trip" is difficult for the average person to perceive.
Calculating that "round trip" latency is a bit difficult as there are a lot of pieces to the puzzle. The "latency" figures reported by a VI or DAW or ASIO driver alone are rather useless. Some of the components you just can not change. A simplified picture for a very fast system might look like:
-Trigger key sensors and send midi data to audio interface (>1ms)
-USB and ASIO driver buffers - in & out + VI processing (>4ms) ****
-D/A conversion (~0.5ms)
-Sound from speaker to eardrum (~3ms per metre)
So "round trip" latency between key trigger and headphone output might be ~6ms (or ~9ms with loudspeakers).
This varies for every system. For example, a very fast system (good computer & good drivers) might allow you to get PianoTeq to run at say a sample rate of 48KHz with a buffer size of 48 (1ms "reported" by PianoTeq). A slower system might requre a larger buffer size to prevent dropouts/crackling sounds (say a buffer size of 512 (10.7ms "reported" by PianoTeq).
Also, if your digital piano has USB MIDI, you might not bother with an audio interface (although maybe something like ASIO4ALL could boost performance).
Apple has some good plug-and-play audio performance (there are some hidden buffers but still good performance).
Linked below is a comprehensive study of latencies with different audio interfaces (optimized drivers = low latency). PCIe is "best" but really overkill for most of us. There is not much ThunderBolt gear available and some "underperforms" (Thunderbolt still requires a clunky controller board inside your computer, drivers are inmature...). USB interfaces with good drivers perform fine for most of us (USB3 is just as fast as USB2 for our purposes). Firewire and PCI interfaces are not generally sold anymore:
https://www.gearslutz.com/board/music-c...-base.html
Presonus wrote an article providing a simple summary of typical processes with computer music latencies. It is marketing and it is old so take it with a grain of salt: https://forums.presonus.com/viewtopic.php?p=95740
DAC speed should not concern you as a general matter. Assume 0.5ms. However, some FPGA are slow (e.g. Chord does not recommend some of its DACs for VIs). On the other hand, RME uses FPGAs to produce very low latency interfaces.
Of course, there is some natural latency with a grand piano. For example, it takes some time for the key stroke to activate mechanics inside the piano to produce sound (there are some interesting studies on that). And it takes time for sound from say the strings and soundboard to travel to the ears (say 3ms per metre).
So, jitter may be more important than latency. That is tougher for users to measure and evaluate. RME interfaces, for example, market jitter reduction as a key feature.
Last edited by music_guy (06-04-2018 17:22)