The iRig Pro Duo I/O offers both 48 kHz and 44.1 kHz, although I only tested using our standard 48 kHz/24-bit (see Enter the 48 kHz alliance). I would never use 44.1 kHz for the reasons explained there. For example, if you want to keep your rig portable and use condenser microphones, you’ll need an interface that supplies phantom power. Maybe you plan on recording guitar and vocals at the same time; then you’ll need enough inputs that also allow simultaneous recording. Min load condition is as follows: music playing, phantom power OFF. This side includes the input for optional external power and MIDI You have to use batteries and headphones when connected to an iPhone (8). The latter was not clear from the manual, but not a problem. It does come with all the cables you need to connect to iPhones or iPads, Android devices, USB, or Macs. That's quite neat, so you don't have nasty surprises when it comes to cables. Everything you need is included, including a set of batteries.

Many of these interfaces are designed to work with mobile devices foremost and are small and powered by USB or disposable batteries. Some were originally designed for computers and later updated to run with mobile. There’s a bit of a tradeoff with the latter; while you may typically get better preamps, their power draw can make them less flexible for portable rigs. The best mobile interfaces to buy at a glance: Even if used with a dynamic microphone without phantom power, the iRig Pro Duo I/O requires a pair of AA batteries (included). The battery life is quoted as:

Balanced line outputs

In addition to being an amp modeler and effects processor, AmpliTube also provides recording capabilities.

Vocal recording is surprisingly good – easily good enough for podcasts and up there with more expensive interfaces – and it's easily one of the cheapest and most flexible solutions for connecting up a high-quality condenser mic up to a range of mobile and desktop devices. Instrument recordings are just as good and it's able to deliver the weight and range it should with minimal noise only really evident at higher input levels. iOS Devices: Compatible with iPhone XS Max, iPhone XS, iPhone XR, iPhone X, iPhone 8 Plus, iPhone 8, iPhone 7 Plus, iPhone 7, iPhone SE, iPhone 6s Plus, iPhone 6s, iPhone 6 Plus, iPhone 6, iPhone 5s, iPad Pro 10.5-inch, iPad Pro 12.9-inch (2nd generation), iPad Pro 9.7-inch, iPad Pro 12.9-inch (1st generation), iPad Air 2, iPad Air, iPad mini 4, iPad mini 3, iPad mini 2, iPad (6th generation), iPad (5th generation), iPod touch (6th generation). iOS 7.0 or later is required. Thanks to its balanced audio output via TRS 1/4”, the Rig Pro Duo I/O can be conveniently used to connect to powered monitor speakers like the following from IK Multimedia: Max load condition: both inputs connected to two 1,5mA phantom powered loads, input gains set to maximum, outputs set to maximum. Once this is done you're ready to record in Audacity, just like you would in the AmpliTube software.This is meant to be an easy style plug-n-play connection, sorry to hear of these continued snags along the way! Which 'lapel microphone' are you using exactly? This may be a factor.