As a 40+ year retired peddler of decent audio gear, here’s are my comments for your friend:
My favorite church reader board displayed the message: "A good friend stabs you in the front." This isn’t going to be gentle, but your friend needs to be put in a headlock and taken to the carpet.
A rep/friend of mine were discussing a dealer who had been in business for 30 years down the street and had become dormant/irrelevant for quite some time. His comment: "He’s got one year of experience -- 30 times!" Reminds me of your friend.
"Retailers" have to reinvent themselves continuously. The goal of "lighting them up" when customers cross your threshold is obtainable and sustainable. If you’re creative, and want to work hard enough. A guy who asks a non-industry friend about what brands to sell probably should be doing something else at this point in his life. He may have crossed the event horizon where there is no escaping the black hole of business failure. The gravitational forces may be so strong that not even high resolution audio can escape it. It sounds like your friend was good at riding the wave of the glory days of "consumer" audio, but doesn't know how to crate his own momentum when the waves crashed on the beach.. A poster once read: "When there's no wind -- row!!"
I’ve seen the prostitution of "specialty audio" brands up close and personal throughout the years. It is ugly, heartbreaking, and unprofitable. It also converts the very fine people working for you into mere brokers of audio gear, rather than audio consultants. You need those brands for promotion to build traffic, to hit "popular" price points, or have some brand familiarity with newbee customers. I can also say that once those brands are established at Big Box, the illusion will be that they will always get a better deal there. I am certain that a half price sale on those items at my store would not have been a traffic builder. I am also certain that 50% off on bad-sounding equipment is still bad...sounding...equipment.
Here are some basics:
There are transaction-basedl customers and relationship-based customers. The transaction-based customer fears not getting the best deal that day. The relationship-based customer fears not buying the right product from the right dealer. It’s good to know the difference. Make sure you are overprepared to service the latter.
People spend money on what their attention is on. ANY excuse to get in contact with your customers is a good one. I required my salespeople to do immediate followups to ANY sale (even $5) to see if the customer is okay with the purchase, needs technical assistance, etc. I also REQUIRED 6-month follow ups. This can get a little tricky because it is not allowed in some areas. My rule was that there could NEVER be an attempt to sell anything. Just a good will call to see how they are getting along with the item. There are 3 benefits for the dealer here: 1) customers are genuinely appreciative of the concern for their well being, 2) their attention is back on hifi for a moment. They may have had root canals, back to school, transmission rebuilt, new bike, etc in those past 6-months and thought very little about hifi. For a brief moment in time they are thinking about how much that like (or dislike) their audio system. And, 3) every now in then, someone will ask: "Hey, I was thinking about putting sound out on the patio. Do you do that?" In that case, you can load up a couple of rock speakers and inground sub and be there while there’s still a head on the beer they just poured.
Service? Keeping old gear with a strong emotional attachment from going into the dumpster can be rewarding and profitable.
Differentiate. Make sure the customer understands that EVERY aspect of your business is superior to Big Box in every way.
Research the brands you want to carry. As mentioned by others, he may not qualify for a number of reasons. A store dominated by "popular" brands may be a disqualifier. Your dealer friend should be fluent in "legit hifi brands" by now, but if not it’s up to him to do the research, fall in love with a group of (protentially profitable) components, and bursting at the seams to tell the world about them. If not, what’s the point?
The profound statement: Learn/teach your staff how to use this. I call this the "profound statement" -- something you say that makes the customer want to hear the rest of your pitch. When asked about a Big Box brand, a comment might be: "The only similarity between (my amp, and theirs) is that that they both have power cords in the box and on/off switches. Everything else is different." Or, "You can’t overspend on a source component." Or, "Are you wearing Depends? I don’t want to be responsible for what happens when you sit in front of these speakers." You have to know your audience here. Some react differently to various communication styles (and, humor).
Sustain the "hifi culture". Pretty self-explanatory, but critical. It never stops. Keep it fresh, and exciting.
If none of that works, I’ve heard that putting an EV charging station in front of your business can be beneficial. Spin a record while you’re charging your Tesla?