Just bought both the 3.5 amp and cd player. Would it be advisable to purchase the x-10v3 in between?
You're a notch up from me. I bought the X-Ray and the X-150 when they first came out (and cost, before the price reduction, about what your new stuff did). I used them for several months with great satisfaction and then auditioned the tube buffer in my home with 30 day return privileges. The change in the sound was immediately discernable and right up my alley. Sound is warmer and well suited to my musical taste. When I bought the X10v3, I also bought the XPSUv3 (outboard power supply for the buffer - also works with my headphone amp and improves performance of both.) If you're inclined toward warmer less clinical mids and highs, I'd say go for it and get the XPSUv3 as well. Best way to decide, though, is to get a dealer that will give you a chance to make the with/without comparison in your own system.
I am just curious, so please don't take this the wrong way; are you unhappy with the 3.5's sound? Are considering the x10v3 in between to solve a particular problem or was it part of the overall plan from the start? I am considering the 3.5 and the 5 integrateds from MF as well. Love to hear your thoughts on the 3.5 without the buffer, as well as after, if you decide to go forward with it. I'd also be interested to hear if you auditioned the 5 vs. the 3.5 before you purchased the 3.5. Also, what type of speakers are you driving with the 3.5?