diff --git a/share/man/man4/snd_hdsp.4 b/share/man/man4/snd_hdsp.4
--- a/share/man/man4/snd_hdsp.4
+++ b/share/man/man4/snd_hdsp.4
@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd May 1, 2024
+.Dd September 28, 2024
 .Dt SND_HDSP 4
 .Os
 .Sh NAME
@@ -56,7 +56,7 @@
 .Pp
 .Bl -bullet -compact
 .It
-RME HDSP 9632
+RME HDSP 9632 (optional AO4S-192 and AIS-192 extension boards)
 .It
 RME HDSP 9652
 .El
@@ -86,7 +86,7 @@
 .Bl -column "Sound Card" "Single Speed" "Double Speed" "Quad Speed"
 .Sy "Sound Card" Ta Sy "Single Speed" Ta Sy "Double Speed" Ta Sy "Quad Speed"
 .It "" Ta "Play | Rec" Ta "Play | Rec" Ta "Play | Rec"
-.It HDSP 9632 Ta " 12  |  12" Ta "  8  |   8" Ta "  4  |   4"
+.It HDSP 9632 Ta " 16  |  16" Ta " 12  |  12" Ta "  8  |   8"
 .It HDSP 9652 Ta " 26  |  26" Ta " 14  |  14" Ta "  -  |   -"
 .El
 .Sh SYSCTL TUNABLES
diff --git a/sys/dev/sound/pci/hdsp-pcm.c b/sys/dev/sound/pci/hdsp-pcm.c
--- a/sys/dev/sound/pci/hdsp-pcm.c
+++ b/sys/dev/sound/pci/hdsp-pcm.c
@@ -107,7 +107,7 @@
 			slot_map |= (0x03 << 8);  /* 2 channels SPDIF. */
 		if (ports & HDSP_CHAN_9632_LINE)
 			slot_map |= (0x03 << 10); /* 2 channels line. */
-		if (ports & HDSP_CHAN_9632_EXT_BOARD)
+		if (ports & HDSP_CHAN_9632_EXT)
 			slot_map |= (0x0f << 12); /* 4 channels extension. */
 	} else if ((ports & HDSP_CHAN_9652_ALL) && (speed <= 96000)) {
 		/* Map HDSP 9652 ports to slot bitmap, no quad speed. */
diff --git a/sys/dev/sound/pci/hdsp.h b/sys/dev/sound/pci/hdsp.h
--- a/sys/dev/sound/pci/hdsp.h
+++ b/sys/dev/sound/pci/hdsp.h
@@ -130,10 +130,11 @@
 #define	HDSP_CHAN_9632_ADAT		(1 << 0)
 #define	HDSP_CHAN_9632_SPDIF		(1 << 1)
 #define	HDSP_CHAN_9632_LINE		(1 << 2)
+#define	HDSP_CHAN_9632_EXT		(1 << 3) /* Extension boards */
 #define	HDSP_CHAN_9632_ALL		(HDSP_CHAN_9632_ADAT | \
 					HDSP_CHAN_9632_SPDIF | \
-					HDSP_CHAN_9632_LINE)
-#define	HDSP_CHAN_9632_EXT_BOARD	(1 << 3)
+					HDSP_CHAN_9632_LINE | \
+					HDSP_CHAN_9632_EXT)
 
 #define	HDSP_CHAN_9652_ADAT1		(1 << 5)
 #define	HDSP_CHAN_9652_ADAT2		(1 << 6)
diff --git a/sys/dev/sound/pci/hdsp.c b/sys/dev/sound/pci/hdsp.c
--- a/sys/dev/sound/pci/hdsp.c
+++ b/sys/dev/sound/pci/hdsp.c
@@ -74,6 +74,7 @@
 	{ HDSP_CHAN_9632_ADAT,    "adat" },
 	{ HDSP_CHAN_9632_SPDIF, "s/pdif" },
 	{ HDSP_CHAN_9632_LINE,    "line" },
+	{ HDSP_CHAN_9632_EXT,      "ext" },
 	{ 0,                        NULL },
 };