Practical advice - if your music is AAC/MP3 or you stream Apple Music, Spotify, Pandora, etc. no need for any OTG or lightning cable. Just use AptX bluetooth or AAC bluetooth (iOS). Since Q5 BT implementation bypasses the BT DAC and goes directly to the dual AKM4490, the quality is just as good as a physical USB connection. If you use Tidal or have mostly lossless files (FLAC, ALAC, AIFF, WAV, etc.) then you may get marginally better sound using USB. However, USB itself introduces it's own limitations so the tradeoff may not be worth. Personally I will be using BT exclusively when I am on the go. At home I will use coax input.