Fosi Audio P4 Preamp Review: A Budget Gem With Room to Grow

When it comes to budget-friendly audio gear, few brands have built a reputation quite like Fosi Audio. Their P4 preamp is no exception—at just around $99, this small but mighty unit brings serious value to the table.

Matt Coykendall recently shared his hands-on review, and we've distilled his insights into this blog for those looking to level up their audio stack without breaking the bank.

First Impressions: Solid Build, Classic Fosi Aesthetics

Right out of the box, the P4 impresses with its aluminum chassis and minimalist design. And yes, it wouldn’t be a Fosi product without that signature orange flair—love it or not. Despite the low price, the build quality punches well above its weight.

Value vs. Convenience: Separates or All-in-One?

Matt raises an important question: Should you build your audio setup from individual components or opt for a one-box solution? The P4, when paired with a Fosi amp and DAC, offers excellent specs and performance—but at around $500 for the full stack. Compare that to something like the Yamaha AS301 for $350, which combines everything in one. The trade-off? You gain in performance and flexibility with separates but might sacrifice some convenience, like integrated headphone amps or speaker switching.

Connectivity & Features: Best in Class at the Price

The P4 excels in connectivity for its price bracket:

3 RCA Inputs
Standard RCA Output
Dedicated Preamp Output (volume-controlled, usable for subwoofers)
Tone Control Bypass
3-stage Gain Switch (3/6/9 dB)

While it lacks XLR outputs—a potential downside for some—it still outperforms many competitors. A motorized volume knob (remote-controlled), bass and treble adjustments, and swappable op-amps make it a tinkerer's delight.

Sound Quality: Transparent and Neutral

Sonically, the P4 is a "what you put in is what you get out" type of preamp. It’s clean, neutral, and transparent—ideal for users who prefer uncolored sound. And for those who do enjoy tweaking, the tone controls do a respectable job. Just keep adjustments subtle to avoid distortion or coloration.

Ideal Use Case: Desktop Setups

The P4 truly shines in desktop configurations. Pair it with Fosi’s ZA3 amps, V3 monos, and ZD3 DAC, you've got a capable, compact, and great-sounding stack. Whether you're streaming, spinning vinyl, or just need a clean preamp for your PC audio, this unit delivers.

What Could Be Better?

Matt also shared a wishlist that could take the P4 from great to exceptional:

High-Pass Filter: Especially useful for bookshelf speaker setups.
Standardized Enclosure Sizes: To better stack with other Fosi gear.
XLR Connectivity: To match the rest of the product line.
12V Trigger: For smoother power-up coordination with other gear.

While these omissions aren’t deal-breakers, their inclusion in future models could elevate the P4 into a higher category—possibly at a slightly higher price point.

Final Thoughts: A Gateway to Hi-Fi

The Fosi Audio P4 isn’t perfect, but it’s a standout in the sub-$100 category. For newcomers to Hi-Fi or those looking to upgrade their desktop audio, it offers serious bang for the buck. Clean sound, thoughtful features, and great build quality—what more can you ask for?