WinWarbler enables you to select separate soundcard devices for transmission and reception. On the Config window's Soundcard tab, the PSK & RTTY Reception panel displays up 16 installed input devices, and the Transmission panel displays up to 16 installed output devices. In the Transmission panel, separate PSK & RTTY and Phone sub-panels provide the option of selecting separate soundcard output devices.
Note that Windows will alert you to various events by playing sounds on the soundcard you designate as the default Windows soundcard. To prevent such sounds from being transmitted while you are operating in PSK, RTTY, or Phone, install a second soundcard for use with these modes, and configure the first soundcard to serve as the default Windows soundcard.