What makes a good piece of audio gear ?

There are no secrets or magic involved. It's a mature industry, and has been for decades. A great piece will be one that meets your particular requirements and will be very reliable. Build quality is real, high quality components is not. All else is marketing and one-upmanship. Did I mention reliability? The more exotic or complex, the greater the failure rate.
Cheers

Luck. I say this after building a few things like speakers and passive preamps and having no talent.

Rok2id what do you mean by saying " high quality components is not"?
I wound think that this is a very important issue to designers and manufacturers;high failure either caused by bad design or a lower quality of parts selected creates bad press and results in product not being sold;if they fail in the warranty period there is extra cost now involved and will lower the margins.

First and foremost, speakers that sound great in your room. Make, model etc. does not make a difference. Let your ears tell you, the expression 'you will know it when you hear', true today as ever.

No matter the design (did I just say that? LOL), one always reads in a review how they end up testing with 'their' ears. So, as long as ears don't change with the one who heads development, a 'house sound' will exist from one model to the next with clarity and detail improving as one model supercedes the next.

And, as long as ears are different from one individual to the next, their will be no concensus from one brand to another, resulting in a high variation of what is considered accurate and/or pleasing, making your question moot at best.

It will all boil down to what you like, others ears be damned.

All the best,
Nonoise