In my opinion, the most important part of a headphone review, is to first understand the sound preferences of the reviewer. All descriptions of a headphone are irrelevant unless you have a reference point for the reviewer.
What headphone(s) does the reviewer like and prefer? And what qualities of a headphone does the reviewer value?

WHAT'S YOUR (P) REFERENCE

So before I talk about Sendy Audio's current flagship headphone, the Peacock, I want to talk a little bit about the ZMF Verite (open). The Verite is my reference and preference headphone.

The Verite is my favorite headphone of all time, at any price. It has this uncanny ability to, simultaneously, sound highly detailed and smooth at the same time. In my opinion, this is a supremely difficult formula to master.

It also has a fairly wide and holographic soundstage. And although it's not the widest that I've heard, it can make it sound like sounds are popping out from behind your head. I love that soundstage effect.

Of course anyone who has ever seen a ZMF product knows they're gorgeous to look at and are built impeccably by hand. They're also very comfortable due to a fantastic headband system. So to me, they represent the total package.
So those are the qualities in a headphone that make me smile. By the way, I fully acknowledge that the Verite is not a "neutral" headphone.

WHAT DO YOU LIKE

In general, I prefer headphones that don't stray too far from neutral, but lean more towards the smoother end of the spectrum, as I am moderately sensitive to upper mids and treble harshness.
That said, I don't want a headphone that lacks detail and resolution (appropriate for its price point).

For example, I love the detail, resolution, and soundstage of the Sennheiser 800S, but it's too fatiguing for me to listen to for a prolonged period of time. So that being said, you know I'm not going to like the tuning of many Beyerdynamics, Grados, or Ultrasones.

WHAT DID YOU USE

So for my review, most of my listening was done with the Singxer SA-1 amplifier in low gain and Modius DAC. I mainly listened to the Peacock balanced, since the Singxer is a balanced amp. I chose the SA-1 so that I could quickly switch between the Verite (XLR) and Peacock (4.4mm) while both were running balanced.

WHAT'S THE COMFORT AND BUILD LIKE

The build quality is simply excellent for its price. The Peacock is made almost entirely of wood, metal, and high quality leather. It absolutely shames the flimsy, plastic build of the Hifiman Arya. And in spite of the use of premium materials, it's still very comfortable to wear. The earcups allow some swivel and the clamping force is light-moderate.

Compared to something that costs more than it, like the HEDDphone, it still comes out on top. While the HEDDphone is made fairly well, it uses a lot more plastic, is much heavier in weight, and has a much higher clamping force. As a former owner of the HEDDphone, I can personally say that its lack of comfort was a deal breaker. For all the premium materials of the Peacock, it's still much lighter and much more comfortable.

I think it's built better than the entire Audeze LCD 2,3, and 4(since they're all built the same). Audeze does use premium materials but I have had too many problems with their headband system. For some unknown reason, Audeze doesn't create enough space between the headband and comfort strap. So when worn, the comfort strap will come into contact with the metal headband, which will quickly create a hot spot. I had no such issue with the Peacock and I had the headband at full extension. I also find it inexcusable that Audeze uses glued on earpads for their entire LCD line, including the 4 and 4Z, that retail for $4000! The Peacock is nearly 1/3 that cost so they get a pass to use any method they like to mount their earpads.

Serious question though: why can't more companies use super, user-friendly magnetic earpad attachments like Abyss, Meze, and Ultrasone?

WHAT ABOUT THE BASS

The bass is fairly solid and definitely not lacking. The sub bass is present and doesn't sound like there's much roll off down to 20hz. The mid bass sounds just a little north of neutral by maybe 3 or 4 db's, which I like. To my ears, completely neutral bass just doesn't give music enough body and soul.

I think the quantity of the mid bass is just about perfect, but it sounds just a tad spongy. I would prefer it to be tighter, but I'll take a little spongy over anemic every day of the week. It doesn't hit quite as hard as the Verite or decay as fast, but at half the price, it's no slouch! I'd say the bass quantity sits between the Verite and Auteur.

On some tracks, the mid bass can sound a little subdued, even though I said earlier that it has sufficient quantity. But I think that is more of a tuning issue of the mids, rather than the amount of bass. I'll talk more about this next.

WHAT ABOUT THE MIDS

The mids are where I have a little issue with the Peacock. There is a broad elevation somewhere in the neighborhood of 900hz - 2khz. And then it is followed by an upper mid recession, and a toned-down treble region as well.

This presents a small problem because it throws off the tonal balance and higher order harmonics. I think this tuning makes it harder to pick out finer details. We all know that a higher volume will bring out more mid bass impact as well as treble detail, due to the Fletcher-Munson curve.

But the Peacock already has extra energy in the low-mids, so if you try to turn up the volume to bring out more of the bass and treble, then the mids can become a little shouty. I actually don't think the Peacock lacks detail for its price point, but the stock tuning can make it seem that way. In my opinion, the balance amongst the lower mids, upper mids, and treble needs a little work.

WHAT ABOUT THE TREBLE

The treble of the Peacock is on the more relaxed and smooth side. As someone who does not like bright headphones, I tend to prefer this type of tuning. However, this has to be balanced with the rest of the frequency spectrum or music can sound dull and lifeless.

Again, I think the treble quantity is actually sufficient for detail, if the lower mids weren't so elevated and the upper mids weren't so recessed. But based on the tuning as it is, I feel the Peacock could use a tad more treble energy. But then that opens up another can of worms, because if you EQ more treble, then you're going to have to EQ more bass. In my opinion, Sendy Audio would have covered a multitude of sins if they simply had a flatter tuning of the mids.

AT THE END OF THE DAY

At the end of the day, I really enjoyed the Sendy Audio Peacock. In general, it is tuned more towards my preference, as I don't like bright headphones. It is built well, comfortable to wear, includes a high quality cable, and has an exceptional soundstage. It's ability to create "ambience" might be its greatest strength. It's certainly my favorite part of it.

In all honesty, the Peacock reminds me of the Audeze house sound, but with a better stock tuning (even though it could also use a little EQ), and a significantly wider soundstage. From a pure enjoyment standpoint, I'd take it over the entire LCD line except the LCD 4. It's just a more enjoyable listen.

However, I do have to say that I think Sendy took it just a smidge too far towards the smooth and relaxed end of the spectrum.

Compared to the Verite, the Peacock lacks a little refinement and articulation. Since it's a planar and the Verite is a dynamic, you'd expect more snap in the transients or leading edges of notes. But that is not the case. Sounds from the Peacock have a little extra butter on them. I guess I'm saying some may find the Peacock smooth to a fault.

I like the extra body in the lower mids, because it prevents the mids from sounding lean or anemic. But you need to balance that extra energy out with the upper mids and treble for clarity.

But what it lacks in refinement, it makes up for with "atmosphere". With the right recording, the Peacock can make a normal track almost sound binaural. It just has such great width to its soundstage that it can "paint" music with a large canvas. So ambient and electronic music sound downright majestic on it. Actually, anything mixed to take advantage of soundstage sounds great with these; think Hans Zimmer for example.

It's smooth tonal balance does also mean it's very forgiving of poor recordings. I really think the Peacock strikes a nice balance between technical and fun. It extracts sufficient detail for its price point without ever sounding sterile.

In terms of only technical proficiency, it neither competes with the summit-fi offerings from Abyss or Hifiman, nor does it's price stake that claim anyway. But I do place it at the top end of mid-fi. But when you factor in the total package of build quality, cable quality, accessories, comfort, and staging ability, it extends closer to summit-fi than many other headphones in its pricing hierarchy.

FOR WHOM DO YOU RECOMMEND

I recommend the Peacock to anyone who likes the Audeze LCD house sound but has always wanted more soundstage than they offer. If you prefer headphones that are on the smoother and more forgiving side, then these are for you.

If you prefer a bright and analytical sound like the Hifiman HEK line, Abyss Diana Phi, Sennheiser hd 800, Beyerdynamic T1, etc., then these are not for you.

If you liked the trippy soundstage of the Hifiman Arya, but wished they weren't so etchy and bright in the upper mids and treble, then you need to audition these. The soundstage of the Peacock is not as tall as the Arya, but it's even wider.

If you like the ZMF Verite but can't afford it, these may make you smile for half the price.

If you like the tuning of the ZMF Auteur but find it just a tad too neutral, you may want to try these.

If you like the more relaxed sound of the Sennheiser HD650, and are looking for an upgrade path with a similar tonality, then put these on your list.

If you love the staging capability of the Sennheiser 800S, but want more bass, less brightness, more soul, and don't mind sacrificing a little detail and technical proficiency, then take these for a ride.

If all you care about is technical performance, you are not impressed by soundstage and ambience, and you always want your coffee black and never with cream or sugar, then sashay away from these.