Running an 8 ohm min head through a 16 ohm max speaker

I decided that I am going to buy a Boss Katana 100 mk 2 head with a peavey 1x12 cab, but and it says 8 ohm minimum but the cab says 16 ohms maximum so i need to know if I should run the head through to that speaker

Short answer is in bold but this post is loaded (no pun intended) with amp and speaker info that everyguitarist should know:

Input impedance has no effect on the speaker, just don't exceed the maximum WATTAGE. Double the amp's rated wattage is a good rule of thumb these days. The speaker's not practically 'seeing' an impedance at all, the amp presents a resistance to return current. The amount of resistance is immaterial to the life of the speaker but it does effect the tone, it's called damp7ng. Low damping is part of the tube amp sound. Speakers are a very low impedance load that is driven by power.

The speaker on the other hand *IS what Ohm called an impedance, it behaves as an inverse resistance to the volrage output from the amplifier which is designed for specific impedance loads in order to amplify properly or even work. The relationship between that output voltage to the impedance it is being asked to drive determines how efficiently that voltage can create mechanical power at the voice coil which we measure in watts, the harder it gas to fight, the more voltage is wasted and the lower the power you're getting from that amplified AC voltage. Wheew*

This should be matched in a tube amplifier, class A or the more common AB, or you risk blowing the output transformer (which is designed to take the speaker impedance and step it up to a level the power tubes can drive or step the output down to speaker driving levels depending on your point of view) , it does other stuff in mist amps but don't worry about that, it's not impedance related). If you must mismatch, low amp ohms into higher speaker ohms is safer than high into low... sort of like how a high impedance signal right from your guitar output sounds like shit into a low impedance microphone preamp or even a 10kohm line input but plug a direct box in to step the impedance down to like 600-2k ohms and you've got tone. But a power amplifier doesn't bridge impedance the same way as a small signal amp due to the low impedances of speakers so there's a power loss and a tonal and output power change when you run low into high... but don't do it, most tube amps will blow up. High into low will always blow up.

low into high and your amp shouldn't fry, high into low will definitely blow

A class AB solid state amp like you usually run into for guitar on the other hand usually is designed for a minimum 4ohm load (some might be 8, the minimum load is usually printed under the speaker jacks). Don't go below 4 (or stated minimum) or you'll fry the thing, that's the high into low rule. But driving a high impedance approximately halves the power output every time you double the impedance so a typical 4ohm minimum amp rated 50 watts output power will be about 25watts into an 8 ohm load. No harm done to the amp or the speaker as long as the speaker can handle more than 25-30 watts RMS.

Class B isn't used for guitar and rarely for any audio because of the inherent crossover distortion but if you do encounter a class AB amp running close to class B the same rules apply. Match tube amps, respect the stated minimum for solid state.

Then there's class D which is by definition solid state. I generally understand how it works, but never serviced ione built one or even read enough about it to tell you if its fussy with speaker loads... my guess is no because it works on completely differently principles than the traditional class A, AB and B amplifiers we're used to. The low into high rule can be applied here just to be safe. If there's nothing printed on a class D amp, don't assume, consult the manual.

The katana is solid state, not sure if its class AB or class D. If the katana 100 says 8ohm minimum then 16 is fine. Otherwise it would say 8 ohm ONLY... though it might not produce a full 100 watts into 16 ohms. 100 solid state watts is excessive for anything less than a small theater. You'll probably never use that wattage even though 100 tube watts can produce higher SPL per rated watt for various reasons... the speaker doesn't care what the source impedance is, you're fine. The 16 ohms is not a maximum or minimum source impedance, it is the speaker cab's nominal impedance rating as a load for an amp. Do not plug an 8 ohm tube amp into a 16 ohm cab and NEVER PLUG A 16 OHM TUBE HEAD INTO AN 8 OR 4 OHM CAB OR AN 8 INTO A 4... EVER!!! The kartana is solid state and will do fine as long as the speaker has sufficient wattage handling, double rms amp rating is safest (with 8 into 16 I would say a 75-100watt speaker rating will do... lower wattage speakers sound better and you may want to look into an 8 ohm 2x12 with a pair of v30s).

Try reading the katana manual. It'll answer these beginner questions and also walk you through the plethora of features from the digital parts. Its s complicated gadget if you deep dive the thing, it has an app... front panel controls do what you expect mostly though.

And why not just get a combo?

Yes, technically but no... waste of money in this instance ... an impedance matching device here will either cost as much (or more than) a matched speaker and/or throw away the same amount of power as running low into high, give or take a couple watts.

The rule if thumb is "low into high and your amp shouldn't fry, high into low will definitely blow"

However, tube (valve) amp users should only use speakers matched to the rated impedance(s) on the amp's output. not all output transformers are created equal, even from unit to unit in the same batch. I don't care that weber makes an impedance matching box. Just don't. If you can afford a tube amp you can afford (a) matched speaker(s). Mist modern amps offer 3 different transformer secondary windings (4, 8 and 16 ohm taps) on a switch or on different speaker jacks.

Bridget, while you're not technically wrong you're making it more complicated than it has to be. The OP is buying solid state. An 8ohm source goes into 16 fine from a solid state amp. It's a minimum 8ohm rating on the amp and the speaker's 16ohm rating is a nominal load. Fine in solid state. Fine.

You didn't read all the bold. low into high is okay on solid state, but always match a tube amplifier

Advanced info for people with a little experience, understanding and a good attention span: impedance matching devices that are robust enough to use safely at high wattage contain high voltage transformers and will cost more than a speaker swap. You may be thinking you could solder a $1 flame proof high wattage resistor with the same ohm rating as the speaker in series or parallel with the speaker to double or halve the impedance while cutting your output power in half. Just don't try something like this unless you're an experienced tech or can afford to blow up an amp as a learning experience. If you have to mismatch a tube amp keep in mind that it will probably blow if you plug it into a lower impedance speaker than its rated output impedance and it might blow if you go into a higher impedance. A solid state amp loses output power driving a higher impedance but a tube amp tends to produce more power, so if your speakers don't have the power handling for a good 3x the amp's rated wattage you will melt the voice coils, the load on your output transformer will go open or short and your amp will blow up.

Most modern tube amps offer at least 2 common speaker impedance rated output taps on different jacks or a selector switch. Utilize this on stage to match your amp. Be aware of the impedance setting and cabinet ratings before taking a tube amp out of standby. If the amp does not have a standby, verifyall speaker connections and impedances before powering on. Tube(valve) equipment contains lethal voltage even when unplugged!!!!

so to sum up don't mismatch a tube(valve) amp, don't run solid state amps into a speaker rated BELOW the amp's minimum rated impedance, don't scrww around with resistors to match speakers to any amp and don't use a passive impdance matching device unless you really trust the manufacturer and never rely on a cheap or flimsy device regardless of the device's or manufacturer's internet reputation... and don't restate half of what I said unless you're trying to get some kids electrocuted, the bit you picked out was conditional. Do exercise caution and ALWAYS respect the ability of electricity to kill humans and light fires. DO OBTAIN THE OWNERS MANUAL TO YOUR AMPLIFIER AND READ IT UNTIL YOU UNDERSTAND THE CONDITIONS IT WAS DESIGNED TO OPERATE UNDER!

I have been dealing with amplifiers for 30 years... if you haven't, heed the bold print in all of my posts. The non-bold is purely information and should only be applied by people with general electronics knowledge.