Thanks for taking the time to provide some useful information. I have done all the checks you mentioned before. I have tried with 2 Odac's, and a Fiio X3 as a USB Dac, they all exhibit the same symptoms. The noise is more noticeable at around 12-1 'o clock volume. However, when unplugged or plugged to X3's lineout the noise is around 9 'o clock and upward. Directly proportional to the volume level. Also, is it normal for my 3.5mm rca to have some noise when I touch them or turn them around but not on my Grado cable? That bit actually made me think this is a cable problem. I am just using the Grado's atm, I am still awaiting for the Q701 and T50rp so I can't do a test with them. Maybe you are right that this is normal with Grado's because they are efficient and sensitive, I can live with it though as it seems to disappear when I'm playing music, I was just curious as to why or how this happens.
Regarding the tube buying, so it is just a matter of preference?Was this feature just designed to be economical for people that already have other tube-powered devices? Are there no technical dis/advantages between 6V and 12v tubes? When do you need them? So, It's going to be trial and error in case I don't follow other people's choices? Oh, too many questions.
Normally, I'm kind of intimated reading these types of threads. They all start with tube talks, preferences, etc. They don't talk about which type to buy, 6V or 12V, why to buy them, or when do you need these specific type,etc. I will have to read more, I just posted here since the thread is still fresh and I needed specific answers. Thanks for the links.