Ehy guys, I'm pretty new to this world (and this forum), so I'm asking you for advice. I've searched and watched for long trying to find my first audio system: I finally decided for the Sennheiser HD600 (3.5mm) and I need a good DAC and AMP for a total of 150/200€. The best options I found were:

DAC

JDS Labs OL DAC (USB)
Schiit Modi 3

AMP

JDS Labs atom
JDS Objective O2 (Jack 6.3mm and coax input)

Right now I'm trying to get the OL DAC and the O2 (found them for a good price on ebay). Is this a good choice or is it messed up? Do I need to buy other cables to connect HP-AMP-DAC (I know I need a 3.5mm to 6.3mm, but I don't find a good one, can you suggest one?) ?

The last thing, I'd like to buy the HD600 from ebay too, in order to spend less, is it a good idea to spend 200+€ on something without a warranty?