With regards to having more options available for waveform export, my starting point was your website description of the "Audio" Pane for IrMaster found at [Link: harctoolbox.org]

As for waveform modulation options, I would presume that sine waves as default is adequate. However, I noted your own recommended settings in the above mentioned website description stating "48000kHz, 8bit, 1 channel, divide carrier, omit trailing gap, and square wave form". So, I thought why not include the square waveform option.

How would using a smartphone to transmit IR commands emulated using the headphone jack equipped with IR diodes constitute a possible danger to infrared receiving hi-fi equipment such as preamplifiers?

Most remote controls are made cheap, flimsy, inadequate, needlessly complex because they are developed by insular companies that have always ignored the user experience. Smartphones have the ability of providing a fully customizable user interface with the ability to cover both bluetooth and wifi interoperability. However, it is unfortunate that integrated infrared transmission hardware has been neglected or depreciated by smartphone manufacturers, thus leaving users to fend for themselves using hacks. But here we are.