What should I upgrade first on my budget system?

Upgrade power cables.

Serious question: why do you feel the need to upgrade any of them?

If one really bugs you, then that one.

If not, then you have lots of highly recommended upgrades: power cords, interconnects, speaker cables, Nobsound springs, Townshend Pods.

Nobsound springs in particular, awesome upgrade on a budget system. Best $30 you will have spent so far. 

I would look to upgrade the preamp first to a tube preamp.  Organ amps make wonderful audio amps because of the heavy duty transformers they use and the fact that Will Vincent made it, I’m sure it’s an amazing power amp.

Also, I don’t subscribe to the Ivor Tieferbrun philosophy to get the best sources possible because everything else is downhill from there, although it certainly makes a great deal of sense.

I once heard at an audio show an incredible sounding setup by Robin Wyatt, Robyatt Audio that featured an amazing Italian SET amp being played with AER Lamhorn single driver speakers using very run of the mill sources - a Sony close n play tangential TT, a first gen Technics transcription CD player, and a Dyna FM3 tuner.  After hearing this setup, I became a firm believer in great electronics and speakers could make mediocre sources really shine.

A Music Reference RM5 mkII is an excellent sounding preamp that mates well with lots of gear.  I owned one for 5 years and partnered it with several tube and SS amps and it always delivered.  I’ve seen them selling in the $5-700 range and I greatly prefer a tube preamp to go with a tube amp, instead of a SS pre with tube amp.  A tube pre with a SS amp is a preferable combo than the other way around.  Just my $.02.  Thanks.

Thanks for your responses. I do have all anti cables for interconnects and a Morrel power cord. But I don't get DACs yet. Someone said I need a good DAC. Would I need one for my cd player and PONO and preamp? Thanks. 

Rotel, absolutely the Rotel.  Rega Apollo replacement perhaps.  It's the Rotel.  I'm sure of it.  Have fun.