Where does "MidFi" differ from "HiFi" or "LOFI"?

@johnweiss , this is open to debate. In branding you have 3 classes, luxury, standard, and budget. I think you have identified the 3 classes in audio that correspond..

Generally these categories differ by SQ and supposedly by price. I think of budget as boom boxes, low quality headphones, speakers made of low quality plastic, etc.

I think of midfi as gear that sounds better than budget and is sometimes found in big box retailers such as receivers, CD players, and the type of speakers that sound good, but not as good as reference class speakers you would find in a store that specializes in audio equipment.

High end gear is made of high quality parts (hopefully), sounds less like a bad recording and more like what the engineer heard in the studio. Sometimes gear is priced accordingly and sometimes budget or midfi gear ends up sounding closer to the high end category. That is a NEW category often referred to as "giant killer". Most members here like "giant killers" when they can find it. See this thread for examples:

Obviously there is no clear answer since synergy, exact components and personal preferences mater greatly.

Let me take a stab at the mid-fi vs high-fi transition. I’m thinking $5K / component. So, assuming just digital… high-fi starts around the $5K… so $5K for streamer, $5K for DAC, $5K for Preamp, and $5K for the amp, and say $10K speakers. There are a lot of caveats, they must be well chosen to find the best available, and synergistic with your other components, and are in line with your personal preferences.

The next category would be audiophile components. A real jump in performance… for these I would say is around $10K per component… so, this time let’s do analog, Turntable, Phonostage, preamp, amp and $20K speakers.

I doubt agreement is likely. But just as a general rule of thumb from my personal experience. I have been at this for about fifty years and have slowly worked up the hierarchy. My current system is around $20K / component and $32K speakers.

@ghdprentice , do you think it is possible to get the SQ of a system like you described (10K+ per component) from a headphone rig, put together properly??

Budget necessary?

As often the case i agree with  ghdprentice 's math and logic with respect to what is high end.   With each component in that price segment and above you should notice real improvements if you are moving up from. Decent mid fi gear. 

The first real Hi Fi piece I really ever owned was the Zesto Leto preamp.  That thing blew me away and set the future bar for performance across my system.   

High end is synonymous with Hi-Fi, but I’d like to think/hope that high fidelity isn’t compartmentalized just to the high end market.