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The latest version 1.5 has the ability to lock out front panel buttons via the control panel software. All other features of USBPre 1.5 remain the same as the original USBPre hardware. A problem if you are doing calibrated measurements, is that the input volume controls knobs do not move in steps and these cannot be locked. The input volume cannot be set using software mixer either, it seems like it can be set from the WinMLS mixer input volume, but this is not true.

When using music (noise) as excitation, there seems to be cross-talk influencing the measurement. An example of an impulse response measured using music is given below.

Crosstalk

By selecting the time window lower limit after the cross talk part as shown above, this problem should be solved. WinMLS has a feature for automatically detecting the start of the impulse response (Time window settings).

Theoretically, two impulses spaced 10 ms apart (the  distance from the cross talk to the start of the impulse response in the figure above) will give a comb filtering effect with dips every 100 Hz. We did not see much of it in thefrequency response plot, as seen below, where the red curve is using the window as shown in the figure above, while in the blue curve, the window starts from 0 ms.

We tried setting the levels to try to remove this crosstalk part, but we did not manage to do it. But if measuring using sine sweep, we did not experience any crosstalk.