In order to improve the recording, there are four parts of the recording signal chain that may need to be "upgraded".
Well, the monitors are not part of the recording chain, but they are needed to hear what has been recorded.
Anyway, no offense intended, but the mic, preamp and converters you have are low quality for recording solo nylon string guitar. If you are considering getting better equipment, perhaps you could respond back with what your budget is. That way, you should get some help with what new equipment might be purchased.