Patch "ALSA: usb-audio: Add a quirck for B&W PX headphones" has been added to the 4.14-stable tree

@@ -3277,4 +3277,51 @@ AU0828_DEVICE(0x2040, 0x7270, "Hauppauge
 	}
 },
 
+{
+	/*
+	 * Bower's & Wilkins PX headphones only support the 48 kHz sample rate
+	 * even though it advertises more. The capture interface doesn't work
+	 * even on windows.
+	 */
+	USB_DEVICE(0x19b5, 0x0021),
+	.driver_info = (unsigned long) &(const struct snd_usb_audio_quirk) {
+		.ifnum = QUIRK_ANY_INTERFACE,
+		.type = QUIRK_COMPOSITE,
+		.data = (const struct snd_usb_audio_quirk[]) {
+			{
+				.ifnum = 0,
+				.type = QUIRK_AUDIO_STANDARD_MIXER,
+			},
+			/* Capture */
+			{
+				.ifnum = 1,
+				.type = QUIRK_IGNORE_INTERFACE,
+			},
+			/* Playback */
+			{
+				.ifnum = 2,
+				.type = QUIRK_AUDIO_FIXED_ENDPOINT,
+				.data = &(const struct audioformat) {
+					.formats = SNDRV_PCM_FMTBIT_S16_LE,
+					.channels = 2,
+					.iface = 2,
+					.altsetting = 1,
+					.altset_idx = 1,
+					.attributes = UAC_EP_CS_ATTR_FILL_MAX |
+						UAC_EP_CS_ATTR_SAMPLE_RATE,
+					.endpoint = 0x03,
+					.ep_attr = USB_ENDPOINT_XFER_ISOC,
+					.rates = SNDRV_PCM_RATE_48000,
+					.rate_min = 48000,
+					.rate_max = 48000,
+					.nr_rates = 1,
+					.rate_table = (unsigned int[]) {
+						48000
+					}
+				}
+			},
+		}
+	}
+},
+
 #undef USB_DEVICE_VENDOR_SPEC