I run Win7 32bit Ultimate on a Core2Duo system and a whole lot of different Ham Sound Card program and no issues.
** Quote: See no changes in the waterfall when rcvr volume is varied" **
1st of all I gather you have confirmed you do have Audio out at the Ext Speaker. Next would be to raise the Mic Gain Level settings in Win7 to Max.
I would highly recommend also getting away form using the Ext Speaker and Mic Jack for Digital.
Biggest issue with using the Mic Jack is over driving the Audio (ALC) to where you are splattering across the Waterfall. You want very little or NO ALC showing at all.
Next the Ext Speaker Audio level is controlled by the Radio's Volume (AF Gain) Control. I would highly recommend using the DataPort (ACC) 24pins (see page 10 in user manual). Using the DataPort the Volume Control has NO effect on the receive Audio and is at a fixed level.
Now if you do decide to use the 24pin ACC port you should be aware that during TX if the Mic is connected to the Radio there is a chance of having a Hot Mic meaning it can pickup Back Ground Audio/Noise which would mean having to turn down the Mic Gain on the Radio.
Now my Icom 718 which uses a 13pin DataPort also has to have its Mic Gain turned down also. I am running a Signalink USB Interface thru this Port and no problem.
Also try using a different program other than MultiPSK. Digipan is a very user friendly but only supports a few PSK modes. Another very user friendly program is FLdigi at www.w1hkj.com
. It is a MultiMode , MultiOS (Windows, Apple MAC OS and Linux) program which is not as cluttered on the Screen as is MultiPSK.
Good Luck! Lets us know how you make out!
73 de Steve KB6HOH