I love Positive Grid JamUp Pro XT on my iPad, it is an excellent amp modelling app especially for Metal tones but Positive Grid have just taken it to the next level adding a new dimension to their amp modelling features in a new App called BIAS which lets you decide which preamp and power amp tubes to use as well as mic placement. More details in their official press release below, looking forward to testing this app!
Press Release
It’s official! Through a 30-second teaser video, Positive Grid announced their new product called BIAS to be released on November 12th. Of course, the teaser gives some hints about the product: it will feature preamp tube, mic and cabinet selection. Sources confirmed us that BIAS will also feature a significant sonic improvement and an astonishing collection of 36 fully customizable amps, something far beyond the actual category offer. For the moment, the app will be available on iPad devices only.
http://www.positivegrid.com/bias/