In deciding if it is best to put new strings on a piano, you must first be able to justify the costs of restring a piano. The piano should have a good value such as a good quality name (Steinway, Chickering & Sons, Mason & Hamlin,Yamaha, Kawai, etc…) In many cases you do not need to put treble strings on. The bass strings get dirt on them and sound tubby. Replacing a few strings is also not a good idea, because the new one sounds better than the older ones, making a discerning difference in the sound. Always check with a Qualified technician,before moving forward.