Hello,
After having it for a good chunk of time I finally had time to power up my Tsunami. I started out trying to run the self-test, which seems to be failing:

Executing test suite...
# usb_id = 5834303532301531D1D
Read USB ID... OK
# input_offset = 122
Test zero offset... OK
# output_offset_neg = -1244
Test offset adjustment... FAIL
output_offset_neg: -1244 is not between -1168 and -768
# input_amp_6 = 3267
# input_amp_1 = 676
# input_amp_0 = 174
Test amplitude adjustment... FAIL
input_amp_0: 174 is not between -3280 and -2980
# input_freq_1k = 999
# input_phase_1k = 29
Test frequency and phase... FAIL
input_phase_1k: 29 is not between 999 and 1001

When I test on a scope, I see significant ripple/noise on the output, especially at lower frequencies and amplitudes. I can't see as much at frequencies > 1k or voltages above 2 volts, but that could just be due to settings on my scope. I can't attach images directly yet, but an album is below:
http://imgur.com/a/dLwFh

Another album with 1v peak-to-peak, 1khz signal:
http://imgur.com/a/RimiN

Is this normal behaviour? I'm using a 6 foot RG58A cable which has tested good with another function generator. Tried with and without a 50ohm terminator; the only effect it had was to half the amplitude.

Hi, not sure about the cause of the self-test fails (I assume you did connect the output and input of the Tsunami during the test), but there have been some developments with the library itself which might help, you should try downloading the new version from https://github.com/arachnidlabs/tsunami-arduino, overwriting your current Tsunami library (should be within your sketchbook folder). Regarding the noise, yup, that's standard - it's a fixed amplitude ~80KHz switching noise from the negative voltage supply chip...