diff -ur linux-2.6.39.1.orig/sound/usb/card.c linux-2.6.39.1/sound/usb/card.c
--- linux-2.6.39.1.orig/sound/usb/card.c	2011-06-06 06:37:26.000000000 +0200
+++ linux-2.6.39.1/sound/usb/card.c	2011-06-06 07:06:06.000000000 +0200
@@ -461,7 +461,10 @@
 	chip = NULL;
 	mutex_lock(&register_mutex);
 	for (i = 0; i < SNDRV_CARDS; i++) {
-		if (usb_chip[i] && usb_chip[i]->dev == dev) {
+		if (usb_chip[i] &&
+			(usb_chip[i]->dev == dev) &&
+			(usb_chip[i]->ctrl_intf) &&
+			(usb_chip[i]->ctrl_intf->desc.bInterfaceNumber == ifnum)) {
 			if (usb_chip[i]->shutdown) {
 				snd_printk(KERN_ERR "USB device is in the shutdown state, cannot create a card instance\n");
 				goto __error;