How to detect real sample size and number of channels in WAV file?

As pointed out in this question, an excellent utility for this task is MediaInfo.

MediaInfo is a convenient unified display of the most relevant technical and tag data for video and audio files.

geek@liv-inspiron:~$ mediainfo file.wav 
General
Complete name                            : file.wav
Format                                   : Wave
File size                                : 33.6 MiB
Duration                                 : 3mn 19s
Overall bit rate mode                    : Constant
Overall bit rate                         : 1 411 Kbps

Audio
Format                                   : DTS
Format/Info                              : Digital Theater Systems
Mode                                     : 14
Format settings, Endianness              : Little
Codec ID                                 : 1
Duration                                 : 3mn 19s
Bit rate mode                            : Constant
Bit rate                                 : 1 411.2 Kbps
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 44.1 KHz
Bit depth                                : 24 bits
Compression mode                         : Lossy
Stream size                              : 33.6 MiB (100%)

This would confirm that the specific file is DTS with 6 channels, but interestingly that the sample size is actually 24 bits and strangely that the compression mode is lossy.

One can also use this utility via a GUI: mediainfo-gui.