[Nook HD, HD+ Q&A, Help & Troubleshooting] Jon Lee:
Well at least I found a practical use for audio-tool. Apparently our sound chipset is normally configured for low-power operation. You can use audio-tool to change this to high performance.

root@android:/ # audio-tool mix
Number of controls: 71
ctl	type	num	name value
0	ENUM	1	DL1 Equalizer Flat response
1	ENUM	1	Sidetone Equalizer Flat response
2	ENUM	1	AMIC Equalizer High-pass 0dB
3	ENUM	1	DMIC Equalizer High-pass 0dB
4	INT	1	DL1 Media Playback Volume 132
5	INT	1	DL1 Tones Playback Volume 0
6	INT	1	DL1 Voice Playback Volume 130
7	INT	1	DL1 Capture Playback Volume 0
8	INT	1	VXREC Media Volume 0
9	INT	1	VXREC Tones Volume 0
10	INT	1	VXREC Voice DL Volume 0
11	INT	1	VXREC Voice UL Volume 0
12	INT	1	AUDUL Media Volume 0
13	INT	1	AUDUL Tones Volume 0
14	INT	1	AUDUL Voice UL Volume 120
15	INT	1	AUDUL Voice DL Volume 0
16	INT	1	SDT UL Volume 101
17	INT	1	SDT DL Volume 120
18	INT	2	DMIC1 UL Volume 120 120
19	INT	2	DMIC2 UL Volume 120 120
20	INT	2	DMIC3 UL Volume 120 120
21	INT	2	AMIC UL Volume 120 120
22	INT	2	BT UL Volume 126 126
23	BOOL	1	DL1 Mono Mixer Off
24	BOOL	1	AUDUL Mono Mixer Off
25	BOOL	1	DL1 MM_EXT Switch Off
26	BOOL	1	DL1 BT_VX Switch Off
27	BOOL	1	DL1 PDM_DL2 Switch On
28	BOOL	1	DL1 PDM Switch Off
29	BOOL	1	Sidetone Mixer Capture Off
30	BOOL	1	Sidetone Mixer Playback On
31	BOOL	1	Capture Mixer Tones Off
32	BOOL	1	Capture Mixer Voice Playback Off
33	BOOL	1	Capture Mixer Voice Capture Off
34	BOOL	1	Capture Mixer Media Playback Off
35	BOOL	1	Voice Capture Mixer Tones Playback Off
36	BOOL	1	Voice Capture Mixer Media Playback Off
37	BOOL	1	Voice Capture Mixer Capture Off
38	BOOL	1	DL1 Mixer Tones Off
39	BOOL	1	DL1 Mixer Voice Off
40	BOOL	1	DL1 Mixer Capture Off
41	BOOL	1	DL1 Mixer Multimedia On
42	ENUM	1	MUX_VX1 None
43	ENUM	1	MUX_VX0 None
44	ENUM	1	MUX_UL11 None
45	ENUM	1	MUX_UL10 None
46	ENUM	1	MUX_UL07 None
47	ENUM	1	MUX_UL06 None
48	ENUM	1	MUX_UL05 None
49	ENUM	1	MUX_UL04 None
50	ENUM	1	MUX_UL03 None
51	ENUM	1	MUX_UL02 None
52	ENUM	1	MUX_UL01 None
53	ENUM	1	MUX_UL00 None
54	INT	2	Capture Preamplifier Volume 1 1
55	INT	2	Capture Volume 4 4
56	INT	2	Aux FM Volume 3 3
57	INT	2	Headset Playback Volume 7 7
58	INT	2	Handsfree Playback Volume 26 26
59	INT	1	Earphone Playback Volume 15
60	ENUM	1	Headset Power Mode Low-Power
61	BOOL	1	Earphone Playback Switch Off
62	BOOL	1	Spk Right Playback Switch On
63	BOOL	1	Spk Left Playback Switch On
64	ENUM	1	Headset Right Playback Off
65	ENUM	1	Headset Left Playback Off
66	ENUM	1	Handsfree Right Playback HF DAC
67	ENUM	1	Handsfree Left Playback HF DAC
68	ENUM	1	Analog Right Capture Route Off
69	ENUM	1	Analog Left Capture Route Off
70	ENUM	1	TWL6040 Power Mode Low-Power
root@android:/ # audio-tool mix 70 1
root@android:/ # audio-tool mix
Number of controls: 71
ctl	type	num	name value
0	ENUM	1	DL1 Equalizer Flat response
1	ENUM	1	Sidetone Equalizer Flat response
2	ENUM	1	AMIC Equalizer High-pass 0dB
3	ENUM	1	DMIC Equalizer High-pass 0dB
4	INT	1	DL1 Media Playback Volume 132
5	INT	1	DL1 Tones Playback Volume 0
6	INT	1	DL1 Voice Playback Volume 130
7	INT	1	DL1 Capture Playback Volume 0
8	INT	1	VXREC Media Volume 0
9	INT	1	VXREC Tones Volume 0
10	INT	1	VXREC Voice DL Volume 0
11	INT	1	VXREC Voice UL Volume 0
12	INT	1	AUDUL Media Volume 0
13	INT	1	AUDUL Tones Volume 0
14	INT	1	AUDUL Voice UL Volume 120
15	INT	1	AUDUL Voice DL Volume 0
16	INT	1	SDT UL Volume 101
17	INT	1	SDT DL Volume 120
18	INT	2	DMIC1 UL Volume 120 120
19	INT	2	DMIC2 UL Volume 120 120
20	INT	2	DMIC3 UL Volume 120 120
21	INT	2	AMIC UL Volume 120 120
22	INT	2	BT UL Volume 126 126
23	BOOL	1	DL1 Mono Mixer Off
24	BOOL	1	AUDUL Mono Mixer Off
25	BOOL	1	DL1 MM_EXT Switch Off
26	BOOL	1	DL1 BT_VX Switch Off
27	BOOL	1	DL1 PDM_DL2 Switch On
28	BOOL	1	DL1 PDM Switch Off
29	BOOL	1	Sidetone Mixer Capture Off
30	BOOL	1	Sidetone Mixer Playback On
31	BOOL	1	Capture Mixer Tones Off
32	BOOL	1	Capture Mixer Voice Playback Off
33	BOOL	1	Capture Mixer Voice Capture Off
34	BOOL	1	Capture Mixer Media Playback Off
35	BOOL	1	Voice Capture Mixer Tones Playback Off
36	BOOL	1	Voice Capture Mixer Media Playback Off
37	BOOL	1	Voice Capture Mixer Capture Off
38	BOOL	1	DL1 Mixer Tones Off
39	BOOL	1	DL1 Mixer Voice Off
40	BOOL	1	DL1 Mixer Capture Off
41	BOOL	1	DL1 Mixer Multimedia On
42	ENUM	1	MUX_VX1 None
43	ENUM	1	MUX_VX0 None
44	ENUM	1	MUX_UL11 None
45	ENUM	1	MUX_UL10 None
46	ENUM	1	MUX_UL07 None
47	ENUM	1	MUX_UL06 None
48	ENUM	1	MUX_UL05 None
49	ENUM	1	MUX_UL04 None
50	ENUM	1	MUX_UL03 None
51	ENUM	1	MUX_UL02 None
52	ENUM	1	MUX_UL01 None
53	ENUM	1	MUX_UL00 None
54	INT	2	Capture Preamplifier Volume 1 1
55	INT	2	Capture Volume 4 4
56	INT	2	Aux FM Volume 3 3
57	INT	2	Headset Playback Volume 7 7
58	INT	2	Handsfree Playback Volume 26 26
59	INT	1	Earphone Playback Volume 15
60	ENUM	1	Headset Power Mode Low-Power
61	BOOL	1	Earphone Playback Switch Off
62	BOOL	1	Spk Right Playback Switch On
63	BOOL	1	Spk Left Playback Switch On
64	ENUM	1	Headset Right Playback Off
65	ENUM	1	Headset Left Playback Off
66	ENUM	1	Handsfree Right Playback HF DAC
67	ENUM	1	Handsfree Left Playback HF DAC
68	ENUM	1	Analog Right Capture Route Off
69	ENUM	1	Analog Left Capture Route Off
70	ENUM	1	TWL6040 Power Mode High-Performance
root@android:/ #

I'm not real sure where to start as far as mapping.