To check settings

UCA202:

# cat /proc/asound/CODEC/pcm0p/sub0/hw_params
# cat /proc/asound/card0/codec#0

access: MMAP_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2 <-------- will be 4 for iO4
rate: 48000 (48000/1) <------ this changes with the input audio file
period_size: 44100
buffer_size: 88200

FiiO

48kHz and below BLUE

48kHz and above YELLOW

DSD GREEN

# cat /proc/asound/card0/stream0

GuangZhou FiiO Electronics Co.,Ltd FiiO K5 Pro at usb-0000:00:12.2-3, high spee : USB Audio

Playback:
  Status: Running
    Interface = 1
    Altset = 2
    Packet Size = 36
    Momentary freq = 44095 Hz (0x5.8308)
    Feedback Format = 16.16
  Interface 1
    Altset 1
    Format: S32_LE
    Channels: 2
    Endpoint: 1 OUT (ASYNC)
    Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
    Data packet interval: 125 us
  Interface 1
    Altset 2
    Format: S16_LE
    Channels: 2
    Endpoint: 1 OUT (ASYNC)
    Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
    Data packet interval: 125 us
  Interface 1
    Altset 3
    Format: SPECIAL
    Channels: 2
    Endpoint: 1 OUT (ASYNC)
    Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
    Data packet interval: 125 us

# cat /proc/asound/card1/stream0 | grep Momentary

   Momentary freq = 44095 Hz (0x5.8308)