Need help about configuring my laptop's sound system

[Levski]

Hello everyone, I've installed FreeBSD 10 RELEASE on my Dell XPS 14z.
However, the sound system doesn't work correctly. Could anyone here
help me to tell me what's the problem? Thanks in advance.

Output of '% cat /dev/sndstat': 
Installed devices: 
pcm0: <Realtek> (play/rec) default 
pcm1: <Intel> (play)

Output of '% dmesg | grep pcm' 
pcm0: <Realtek> at nid 20,33 and 18 on hdaa0 
pcm1: <Realtek> at nid 24 on hdaa0 
pcm2: <Intel> at nid 5 on hdaa1 
pcm0: <Realtek> at nid 20,33 and 18 on hdaa0 
pcm1: <Realtek> at nid 24 on hdaa0 
pcm2: <Intel> at nid 5 on hdaa1 
pcm0: <Realtek> at nid 20,33 and 18 on hdaa0 
pcm1: <Realtek> at nid 24 on hdaa0 
pcm2: <Intel> at nid 5 on hdaa1 
pcm0: <Realtek> at nid 20,33 and 18 on hdaa0 
pcm1: <Realtek> at nid 24 on hdaa0 
pcm2: <Intel> at nid 5 on hdaa1 
pcm0: <Realtek> at nid 20,33 and 18 on hdaa0 
pcm1: <Realtek> at nid 24 on hdaa0 
pcm2: <Intel> at nid 5 on hdaa1 
pcm0: <Realtek> at nid 20,33 and 18 on hdaa0 
pcm1: <Realtek> at nid 24 on hdaa0 
pcm2: <Intel> at nid 5 on hdaa1 
pcm0: <Realtek> at nid 24 on hdaa0 
pcm1: <Intel> at nid 5 on hdaa1 
pcm0: <Realtek> at nid 33 and 24 on hdaa0 
pcm1: <Intel> at nid 5 on hdaa1

Output of '% sudo sysctl hw.snd':
hw.snd.report_soft_formats: 1 
hw.snd.report_soft_matrix: 1 
hw.snd.latency: 5 
hw.snd.latency_profile: 1 
hw.snd.vpc_autoreset: 1 
hw.snd.vpc_0db: 45 
hw.snd.vpc_reset: 0 
hw.snd.compat_linux_mmap: 0 
hw.snd.feeder_eq_presets:
PEQ:16000,0.2500,62,0.2500:-9,9,1.0:44100,48000,88200,96000,176400,192000 
hw.snd.feeder_eq_exact_rate: 0 
hw.snd.feeder_rate_presets: 100:8:0.85 100:36:0.92 100:164:0.97 
hw.snd.feeder_rate_polyphase_max: 183040 
hw.snd.feeder_rate_min: 1 
hw.snd.feeder_rate_max: 2016000 
hw.snd.feeder_rate_round: 25 
hw.snd.feeder_rate_quality: 1 
hw.snd.vpc_mixer_bypass: 1 
hw.snd.verbose: 0 
hw.snd.default_auto: 0 
hw.snd.version: 2009061500/amd64 
hw.snd.default_unit: 0 
hw.snd.maxautovchans: 16

Output of '% sudo sysctl dev.pcm' 
dev.pcm.0.%desc: Realtek ALC269 (Right Analog) 
dev.pcm.0.%driver: pcm 
dev.pcm.0.%location: nid=33,24 
dev.pcm.0.%parent: hdaa0 
dev.pcm.0.play.vchans: 3 
dev.pcm.0.play.vchanmode: fixed 
dev.pcm.0.play.vchanrate: 48000 
dev.pcm.0.play.vchanformat: s16le:2.0 
dev.pcm.0.play.32bit: 24 
dev.pcm.0.rec.vchans: 1 
dev.pcm.0.rec.vchanmode: fixed 
dev.pcm.0.rec.vchanrate: 48000 
dev.pcm.0.rec.vchanformat: s16le:2.0 
dev.pcm.0.rec.32bit: 24 
dev.pcm.0.rec.autosrc: 2 
dev.pcm.0.buffersize: 65536 
dev.pcm.0.bitperfect: 0 
dev.pcm.1.%desc: Intel Cougar Point (HDMI/DP 8ch) 
dev.pcm.1.%driver: pcm 
dev.pcm.1.%location: nid=5 
dev.pcm.1.%parent: hdaa1 
dev.pcm.1.play.vchans: 1 
dev.pcm.1.play.vchanmode: passthrough 
dev.pcm.1.play.vchanrate: 48000 
dev.pcm.1.play.vchanformat: s16le:2.0 
dev.pcm.1.play.32bit: 24 
dev.pcm.1.buffersize: 65536 
dev.pcm.1.bitperfect: 0

And I don't know how to config the /boot/device.hint. According to the
instruction, (https://forums.freebsd.org/viewtopic.php?&t=30502) ,I try 
appending the following 2 lines to the file and reboot, but it doesn't work:
hint.hdaa.0.nid18.config="as=5 seq=0 device=Speaker" 
hint.hdaa.0.nid20.config="as=5 seq=15 device=Headphones" 

Could anyone here tell me how to correctly config my laptop's sound
system?

Any suggestion will be appreciated.
-- 
Levski Weng