One is just a portable amp the other a DAC with an amp I know, I'm just not so sure a DAC is that necessary for a beginner like me but then there's no harm in getting one especially since A5 and idsd cost the same but then idsd le outputs 150mw at 32ohm and A5 gives 800mw at 32ohm. I am officially torn. I have to get an amp for my new sennheiser hd600 which is about to arrive and I can't decide if I should get a dedicated amp or a well regarded DAC amp. It comes down to sound quality, neutrality, and transparency , which of these 2 is better suited for driving a 300ohm headphone, is the power of the A5 necessary to get the best from hd600 or will the more refined dac and polished amp in idsd get my better clarity and quality. I actually don't need very high volume I like to listen at lower volumes which give a sense of bigger stage, improvement in sound quality is the sole criteria for making the decision, battery, form, volume are all irrelevant. P s suggestions have to be portable, desktop solutions are not an option right now.