That is not supported in our driver (for good reasons). Change the buffer size in the card's Settings dialog.

If you are on windows, you can do that easily with the hdsp utility in systertray. Click on it and change latency. At least here in cubase there is no reason to go into the daw settings. OK it is not a butoon in reaper but it is only 2 clicks.

Just curious: what are those reasons? I have half a dozen interfaces in the house, and RME is only one that doesn't support this. For a company with such a good reputation for drivers, it's surprising that RME is the odd man out here.

Right, but this is another area where the RME driver behaves oddly. If I change the buffer settings in even my cheapy Behringer interface, when I come back to Reaper, those changes are immediately reflected. That makes changing buffer setting a few clicks. With the RME interface I need to open the Reaper audio settings and close it, essentially reinitializing the driver, for the setting to take effect. That means I need 6 clicks to change the buffer settings: open audio settings, click ASIO config, click buffer drop down, click new setting, click OK on the buffer dialog or click back on Reaper, click OK on audio settings.

If the RME driver supported the host requesting a block size, that goes down to two clicks.

REAPER does this perfectly fine here. No need to open audio settings after buffer size change.

But I agree: But I also think that support for buffer size change requests from DAW could be a nice thing to have for some. For security reasons there could be an advanced setting in DSP settings to disable those requests in case it gives troubles.