I am not an SR-7 owner, nor have I heard one. However, that does not diminish in any way interest in what seems to be an excellent product (or other headamps - however, my listening cycle has currently swung back to my speakered gear).
That being said, I understand there are pluses to buying used gear, and have picked up a couple pieces of used gear at fair prices. However, in cases where my discretionary income allows it, I generally prefer to purchase new due to a few factors/preferences. In buying new:
1) I know I should be receiving a completely unblemished, perfect, unabused unit. I try, and think I succeed, in babying my gear including keeping it well maintained and flawless in appearance (I note this is certainly helped by having a dedicated listening room, no small children, and keeping pets out of the listening room.). If I buy new, any defect in it when I receive it will be would be due to the shipping/packaging/manufacturing, all of which allow me recourse and remedy. [The treatment of audio gear by various shipping companies, and purchasers' individual problems with this issue, are more fully discussed in other threads in this and other forums.] I have had to return new products damaged in shipping, and was protected from any loss on my audio investment outside of the time involved.
2) I will have the manufacturer's full warranty. I know it's an imperfect world; even with the best QC, some defect may be present or occur. If a defect presents itself immediately or sometime during the warranty period, my investment is protected. This has come in handy over the years with both audio and non-audio items.
3) With the new component fully burned-in in my system, I may not find it brings the anticipated synergy in my system, in spite of my product research. Numerous quality manufacturers have a limited new purchase return policy, and I may need to avail myself of the policy (this hasn't happened yet), and subsequently only be out the shipping/restocking fee.
4) I have a daughter to whom I can hand down my older, seasoned gear. This saves her $, and has cultivated her own passion with things musical. I find I've held on to audio gear for quite some time (we are talking at least 10 years or so) before upgrading; the exception to this has been tubes, an area that seemingly brings its own set of issues.
5) The price break between buying new or used is not perceived to be significant enough to buy used. I imagine this paradigm differs for each person as to what constitues being "significant" enough.
Just my thoughts on the issue. I also note I'm cognizant of the value in purchasing quality used gear, as well as the risk involved in purchasing used. YMMV.
