I have been playing for quite some time but never passionate enough to know more about equipment until recently.

I am playing with two rackets at the moment – Voltric 80 and Panda Power Trinity 2. The Voltric used to be strung with NBG98 27lbs while the Panda is BG66 Ultimax 26lbs. Between the two I prefer Voltric as I can get more power from smashes. My rackets are strung at such high tension more because a few of my friends started to increase the tension on theirs rather than knowing what I was doing.

One of the weakness in my game is strength. I often find my smash too weak and clearing from baseline to baseline very stressful especially in a more competitive doubles game. 

I have recently changed the string on my Voltric to BG66 Ultimax at 25lbs. I was disappointed to find the new setup worse than the previous one. The power from my smash became worse and my control of net shots and service have deteriorate to the extent that my less preferred racket, the Panda has become my more preferred racket. Hence my dilemma is how to get the best out of my existing two rackets, i.e. in terms of getting the right string at the right tension and whether the two rackets actually suit the me. As I have mentioned before I do not have very good strength and I usually play doubles and I am a leftie.

I just want some technical advice with regards to the racket types, string types and tension for someone with poorer strength. If both the rackets I currently own are not as suitable, I do not mind getting a new one. Few of the rackets I have in mind are Yonex ArcSaber 10, Victor MX80, Victor Brave Sword LYD and Victor MX60 but I am not sure whether they are any more suitable than my current ones. At the end of the day I just want to gain more knowledge on rackets, stiffness, size of sweet spots, strings and tension to assist me in finding the optimum setup. 

Thanks.