Don't worry bro this is a usual thing to happen to beginners U bought the best thing in ur budget now it's time to enjoy to what u've got.
In next step keep in mind u should first change the rear speakers to sony / pioneer and then the pre (tape)
That is a misconception k weight zyada hai to amp acha hoga. Mein ne aise bhi amp dekhe hain jan ka weight kaafi tha lekin jab khol k dekha to andar kuch bhi nahi tha. Its mostly body shell weight only
if u are satisfied with your purchase and its sound quality then whats problem ?