I have a common problem on all freshly-installed Windows Vista platforms here. No matter of the Vista versions (Home Basic, Business Premium) and PC machines, my following experiments always stand with the same results:
//// Target device USB audio device (complying USB 2.0 spec and USB audio spec. 1.0). This device always uses the default "Microsoft Usb Audio driver", no third-party driver.
///// Test cases (a) If it directly connects to PC's USB 2.0 hub, Vista will be enumerated as a "high-speed" USB audio device. (b) If it connects to PC's USB 1.0 hub, Vista will be enumerated as a "full-speed" USB audio device.
///// Procedures (1) Plug-in a USB audio device ( having both capture and render functions) (2) Open "Windows Sound Recorder" (recording on the target device) (3) Open "Windows Task Manager" and look at the CPU usages at "Performance" tab. (4) Start recording ... (5) Observe the CPU usages.
///// Results (1) Test case(a) always consumes 3-5 times of CPU usages than Test case(b). (2) Test case(a) : If I open the "Windows Media Player" (playback on the target device), the CPU usages will be doubled and my PC systems are extremely "hungry" for CPU power.
///// My guess (1) The same device on Windows XP has no such problem (2) Vista at the "kernel" or "driver" level is BAD on handling "high-speed" USB audio device.
///// Ask for your help ...... I can provide more data for your reference.
