In my experience shooting walkthroughs in hollow, untreated spaces, acoustic reflections will ruin audio faster than a cheap preamp. You need tight directional control and proper gain staging to avoid clipping on Sony bodies like your a6400. Over the years, I've tested quite a few budget options and two stand out specifically for sub-$100 budgets.

• Deity V-Mic D4 Duo Dual-Capsule Shotgun Microphone: This unit utilizes a supercardioid polar pattern with a frequency response of 50Hz-20kHz. Pros include excellent off-axis rejection which minimizes room echo, plus a secondary input for lavs. Cons are that the body is entirely plastic and feels a bit fragile.
• <a href=" https://www.bhphotovideo.com/c/search?Ntt= Sennheiser+MKE+200+On-Camera+Directional+Microphone&BI=8941&KBID=10361&SID=12345&DFF=d50" target="_blank" rel="nofollow sponsored">Sennheiser MKE 200 On-Camera Directional Microphone: Features a built-in windscreen and shock mount with a supercardioid capsule. Pros: robust mechanical build quality and fantastic internal dampening against handling noise. Cons: fixed cable design and slightly tinnier high-end response compared to larger mics. Practical tip for your upcoming shoot: set your a6400 internal audio recording level manually around 3 or 4, then boost the gain slightly on the microphone itself if it has a boost switch. This prevents the Sony preamp from clipping when you raise your voice in an empty hallway. Good luck with the gig.

Oh man, dying right before a big shoot is the absolute worst. Don't panic though, you have fantastic options well under your budget that will handle empty echoey houses surprisingly well. Real estate audio is all about cutting out that room bounce, and a tight supercardioid pattern is your best friend here. Here is what you need to grab right now:

• Deity V-Mic D4 Duo
• Amazing value at around 90 bucks. It rejects side noise brilliantly and the audio quality is crisp enough to rival mics twice the price.
• Rode VideoMic GO II
• Coming in right around 99 dollars, this gives you massive clarity and plugs straight into your Sony via USB or 3.5mm without needing a battery. Grab one of these immediately and you will be totally fine on Tuesday!

Saw this earlier but just now getting back to you. Are you using a grip or cage on that a6400? Grab a Rode VideoMic GO II since it has great off-axis rejection for empty rooms.

Just saw this thread pop up while checking the forum. Before you buy anything else right now, what kind of gain staging setup are you currently using on your a6400? I honestly had issues with several budget options clipping constantly in empty rooms because people overlook basic audio fundamentals:

• Never leave your camera audio settings on auto gain when shooting walkthroughs.
• Avoid cheap plastic shock mounts that transfer handling noise directly to the track.
• Do not crank the camera preamp too high, since Sony preamps get noisy fast. Let me know your preamp settings and I can give you a better direction for your Tuesday shoot.